/*----------------------------------------------------------------------------/
/  FatFs - FAT file system module  R0.08a                 (C)ChaN, 2010
/-----------------------------------------------------------------------------/
/ FatFs module is a generic FAT file system module for small embedded systems.
/ This is a free software that opened for education, research and commercial
/ developments under license policy of following terms.
/
/  Copyright (C) 2010, ChaN, all right reserved.
/
/ * The FatFs module is a free software and there is NO WARRANTY.
/ * No restriction on use. You can use, modify and redistribute it for
/   personal, non-profit or commercial products UNDER YOUR RESPONSIBILITY.
/ * Redistributions of source code must retain the above copyright notice.
/
/-----------------------------------------------------------------------------/
/ Feb 26,'06 R0.00  Prototype.
/
/ Apr 29,'06 R0.01  First stable version.
/
/ Jun 01,'06 R0.02  Added FAT12 support.
/                   Removed unbuffered mode.
/                   Fixed a problem on small (<32M) partition.
/ Jun 10,'06 R0.02a Added a configuration option (_FS_MINIMUM).
/
/ Sep 22,'06 R0.03  Added f_rename().
/                   Changed option _FS_MINIMUM to _FS_MINIMIZE.
/ Dec 11,'06 R0.03a Improved cluster scan algorithm to write files fast.
/                   Fixed f_mkdir() creates incorrect directory on FAT32.
/
/ Feb 04,'07 R0.04  Supported multiple drive system.
/                   Changed some interfaces for multiple drive system.
/                   Changed f_mountdrv() to f_mount().
/                   Added f_mkfs().
/ Apr 01,'07 R0.04a Supported multiple partitions on a physical drive.
/                   Added a capability of extending file size to f_lseek().
/                   Added minimization level 3.
/                   Fixed an endian sensitive code in f_mkfs().
/ May 05,'07 R0.04b Added a configuration option _USE_NTFLAG.
/                   Added FSInfo support.
/                   Fixed DBCS name can result FR_INVALID_NAME.
/                   Fixed short seek (<= csize) collapses the file object.
/
/ Aug 25,'07 R0.05  Changed arguments of f_read(), f_write() and f_mkfs().
/                   Fixed f_mkfs() on FAT32 creates incorrect FSInfo.
/                   Fixed f_mkdir() on FAT32 creates incorrect directory.
/ Feb 03,'08 R0.05a Added f_truncate() and f_utime().
/                   Fixed off by one error at FAT sub-type determination.
/                   Fixed btr in f_read() can be mistruncated.
/                   Fixed cached sector is not flushed when create and close without write.
/
/ Apr 01,'08 R0.06  Added fputc(), fputs(), fprintf() and fgets().
/                   Improved performance of f_lseek() on moving to the same or following cluster.
/
/ Apr 01,'09 R0.07  Merged Tiny-FatFs as a buffer configuration option. (_FS_TINY)
/                   Added long file name support.
/                   Added multiple code page support.
/                   Added re-entrancy for multitask operation.
/                   Added auto cluster size selection to f_mkfs().
/                   Added rewind option to f_readdir().
/                   Changed result code of critical errors.
/                   Renamed string functions to avoid name collision.
/ Apr 14,'09 R0.07a Separated out OS dependent code on reentrant cfg.
/                   Added multiple sector size support.
/ Jun 21,'09 R0.07c Fixed f_unlink() can return FR_OK on error.
/                   Fixed wrong cache control in f_lseek().
/                   Added relative path feature.
/                   Added f_chdir() and f_chdrive().
/                   Added proper case conversion to extended char.
/ Nov 03,'09 R0.07e Separated out configuration options from ff.h to ffconf.h.
/                   Fixed f_unlink() fails to remove a sub-dir on _FS_RPATH.
/                   Fixed name matching error on the 13 char boundary.
/                   Added a configuration option, _LFN_UNICODE.
/                   Changed f_readdir() to return the SFN with always upper case on non-LFN cfg.
/
/ May 15,'10 R0.08  Added a memory configuration option. (_USE_LFN = 3)
/                   Added file lock feature. (_FS_SHARE)
/                   Added fast seek feature. (_USE_FASTSEEK)
/                   Changed some types on the API, XCHAR->TCHAR.
/                   Changed fname member in the FILINFO structure on Unicode cfg.
/                   String functions support UTF-8 encoding files on Unicode cfg.
/ Aug 16,'10 R0.08a Added f_getcwd(). (_FS_RPATH = 2)
/                   Added sector erase feature. (_USE_ERASE)
/                   Moved file lock semaphore table from fs object to the bss.
/                   Fixed a wrong directory entry is created on non-LFN cfg when the given name contains ';'.
/                   Fixed f_mkfs() creates wrong FAT32 volume.
/ Sep 14,'12 tisb   Added _VOLUMES check for FatFS initialization (SDOCM00094671)
/---------------------------------------------------------------------------*/

#include "ff.h"                 /* FatFs configurations and declarations */
#include "diskio.h"             /* Declarations of low level disk I/O functions */


/*--------------------------------------------------------------------------

   Module Private Definitions

---------------------------------------------------------------------------*/

#if _FATFS != 8255
#error Wrong include file (ff.h).
#endif


/* Definitions on sector size */
#if _MAX_SS != 512 && _MAX_SS != 1024 && _MAX_SS != 2048 && _MAX_SS != 4096
#error Wrong sector size.
#endif
#if _MAX_SS != 512
#define SS(fs)  ((fs)->ssize)   /* Multiple sector size */
#else
#define SS(fs)  512U                    /* Fixed sector size */
#endif


/* Reentrancy related */
#if _FS_REENTRANT
#if _USE_LFN == 1
#error Static LFN work area must not be used in re-entrant configuration.
#endif
#define ENTER_FF(fs)            { if (!lock_fs(fs)) return FR_TIMEOUT; }
#define LEAVE_FF(fs, res)       { unlock_fs(fs, res); return res; }
#else
#define ENTER_FF(fs)
#define LEAVE_FF(fs, res)       return res
#endif

#define ABORT(fs, res)          { fp->flag |= FA__ERROR; LEAVE_FF(fs, res); }


/* File shareing feature */
#if _FS_SHARE
#if _FS_READONLY
#error _FS_SHARE must be 0 on read-only cfg.
#endif
typedef struct {
        FATFS *fs;                              /* File ID 1, volume (NULL:blank entry) */
        DWORD clu;                              /* File ID 2, directory */
        WORD idx;                               /* File ID 3, directory index */
        WORD ctr;                               /* File open counter, 0:none, 0x01..0xFF:read open count, 0x100:write mode */
} FILESEM;
#endif


/* Misc definitions */
#define LD_CLUST(dir)   (((DWORD)LD_WORD(dir+DIR_FstClusHI)<<16) | LD_WORD(dir+DIR_FstClusLO))
#define ST_CLUST(dir,cl) {ST_WORD(dir+DIR_FstClusLO, cl); ST_WORD(dir+DIR_FstClusHI, (DWORD)cl>>16);}


/* Character code support macros */
#define IsUpper(c)      (((c)>='A')&&((c)<='Z'))
#define IsLower(c)      (((c)>='a')&&((c)<='z'))
#define IsDigit(c)      (((c)>='0')&&((c)<='9'))

#if _DF1S               /* Code page is DBCS */

#ifdef _DF2S    /* Two 1st byte areas */
#define IsDBCS1(c)      (((BYTE)(c) >= _DF1S && (BYTE)(c) <= _DF1E) || ((BYTE)(c) >= _DF2S && (BYTE)(c) <= _DF2E))
#else                   /* One 1st byte area */
#define IsDBCS1(c)      ((BYTE)(c) >= _DF1S && (BYTE)(c) <= _DF1E)
#endif

#ifdef _DS3S    /* Three 2nd byte areas */
#define IsDBCS2(c)      (((BYTE)(c) >= _DS1S && (BYTE)(c) <= _DS1E) || ((BYTE)(c) >= _DS2S && (BYTE)(c) <= _DS2E) || ((BYTE)(c) >= _DS3S && (BYTE)(c) <= _DS3E))
#else                   /* Two 2nd byte areas */
#define IsDBCS2(c)      (((BYTE)(c) >= _DS1S && (BYTE)(c) <= _DS1E) || ((BYTE)(c) >= _DS2S && (BYTE)(c) <= _DS2E))
#endif

#else                   /* Code page is SBCS */

#define IsDBCS1(c)      0
#define IsDBCS2(c)      0

#endif /* _DF1S */


/* Name status flags */
#define NS                      11              /* Offset of name status byte */
#define NS_LOSS         0x01    /* Out of 8.3 format */
#define NS_LFN          0x02    /* Force to create LFN entry */
#define NS_LAST         0x04    /* Last segment */
#define NS_BODY         0x08    /* Lower case flag (body) */
#define NS_EXT          0x10    /* Lower case flag (ext) */
#define NS_DOT          0x20    /* Dot entry */


/* FAT sub-type boundaries */
/* Note that the FAT spec by Microsoft says 4085 but Windows works with 4087! */
#define MIN_FAT16       4086    /* Minimum number of clusters for FAT16 */
#define MIN_FAT32       65526   /* Minimum number of clusters for FAT32 */


/* FatFs refers the members in the FAT structures as byte array instead of
/ structure member because there are incompatibility of the packing option
/ between compilers. */

#define BS_jmpBoot                      0
#define BS_OEMName                      3
#define BPB_BytsPerSec          11
#define BPB_SecPerClus          13
#define BPB_RsvdSecCnt          14
#define BPB_NumFATs                     16
#define BPB_RootEntCnt          17
#define BPB_TotSec16            19
#define BPB_Media                       21
#define BPB_FATSz16                     22
#define BPB_SecPerTrk           24
#define BPB_NumHeads            26
#define BPB_HiddSec                     28
#define BPB_TotSec32            32
#define BS_DrvNum                       36
#define BS_BootSig                      38
#define BS_VolID                        39
#define BS_VolLab                       43
#define BS_FilSysType           54
#define BPB_FATSz32                     36
#define BPB_ExtFlags            40
#define BPB_FSVer                       42
#define BPB_RootClus            44
#define BPB_FSInfo                      48
#define BPB_BkBootSec           50
#define BS_DrvNum32                     64
#define BS_BootSig32            66
#define BS_VolID32                      67
#define BS_VolLab32                     71
#define BS_FilSysType32         82
#define FSI_LeadSig                     0
#define FSI_StrucSig            484
#define FSI_Free_Count          488
#define FSI_Nxt_Free            492
#define MBR_Table                       446
#define BS_55AA                         510

#define DIR_Name                        0
#define DIR_Attr                        11
#define DIR_NTres                       12
#define DIR_CrtTime                     14
#define DIR_CrtDate                     16
#define DIR_FstClusHI           20
#define DIR_WrtTime                     22
#define DIR_WrtDate                     24
#define DIR_FstClusLO           26
#define DIR_FileSize            28
#define LDIR_Ord                        0
#define LDIR_Attr                       11
#define LDIR_Type                       12
#define LDIR_Chksum                     13
#define LDIR_FstClusLO          26



/*------------------------------------------------------------*/
/* Work area                                                  */

#if _VOLUMES == 4
static
FATFS *FatFs[_VOLUMES] = {0,0,0,0};     /* Pointer to the file system objects (logical drives) */
#else
#error Number of initializers must match _VOLUMES.
#endif

static
WORD Fsid = 0;                          /* File system mount ID */

#if _FS_RPATH
static
BYTE CurrVol = 0;                       /* Current drive */
#endif

#if _FS_SHARE
static
FILESEM Files[_FS_SHARE];       /* File lock semaphores */
#endif

#if _USE_LFN == 0                       /* No LFN */
#define DEF_NAMEBUF                     BYTE sfn[12]
#define INIT_BUF(dobj)          (dobj).fn = sfn
#define FREE_BUF()

#elif _USE_LFN == 1                     /* LFN with static LFN working buffer */
static WCHAR LfnBuf[_MAX_LFN+1];
#define DEF_NAMEBUF                     BYTE sfn[12]
#define INIT_BUF(dobj)          { (dobj).fn = sfn; (dobj).lfn = LfnBuf; }
#define FREE_BUF()

#elif _USE_LFN == 2             /* LFN with dynamic LFN working buffer on the stack */
#define DEF_NAMEBUF                     BYTE sfn[12]; WCHAR lbuf[_MAX_LFN+1]
#define INIT_BUF(dobj)          { (dobj).fn = sfn; (dobj).lfn = lbuf; }
#define FREE_BUF()

#elif _USE_LFN == 3             /* LFN with dynamic LFN working buffer on the heap */
#define DEF_NAMEBUF                     BYTE sfn[12]; WCHAR *lfn
#define INIT_BUF(dobj)          { lfn = ff_memalloc((_MAX_LFN + 1) * 2); \
                                                          if (!lfn) LEAVE_FF((dobj).fs, FR_NOT_ENOUGH_CORE); \
                                                          (dobj).lfn = lfn;     (dobj).fn = sfn; }
#define FREE_BUF()                      ff_memfree(lfn)

#else
#error Wrong LFN configuration.
#endif




/*--------------------------------------------------------------------------

   Module Private Functions

---------------------------------------------------------------------------*/


/*-----------------------------------------------------------------------*/
/* String functions                                                      */
/*-----------------------------------------------------------------------*/

/* Copy memory to memory */
static
void mem_cpy (void* dst, const void* src, UINT cnt) {
        BYTE *d = (BYTE*)dst;
        const BYTE *s = (const BYTE*)src;

#if _WORD_ACCESS == 1
        while (cnt >= sizeof(int)) {
                *(int*)d = *(int*)s;
                d += sizeof(int); s += sizeof(int);
                cnt -= sizeof(int);
        }
#endif
        while (cnt--)
                *d++ = *s++;
}

/* Fill memory */
static
void mem_set (void* dst, int val, UINT cnt) {
        BYTE *d = (BYTE*)dst;

        while (cnt--)
                *d++ = (BYTE)val;
}

/* Compare memory to memory */
static
int mem_cmp (const void* dst, const void* src, UINT cnt) {
        const BYTE *d = (const BYTE *)dst, *s = (const BYTE *)src;
        int r = 0;

        while (cnt-- && (r = *d++ - *s++) == 0) ;
        return r;
}

/* Check if chr is contained in the string */
static
int chk_chr (const char* str, int chr) {
        while (*str && *str != chr) str++;
        return *str;
}



/*-----------------------------------------------------------------------*/
/* Request/Release grant to access the volume                            */
/*-----------------------------------------------------------------------*/
#if _FS_REENTRANT

static
int lock_fs (
        FATFS *fs               /* File system object */
)
{
        return ff_req_grant(fs->sobj);
}


static
void unlock_fs (
        FATFS *fs,              /* File system object */
        FRESULT res             /* Result code to be returned */
)
{
        if (res != FR_NOT_ENABLED &&
                res != FR_INVALID_DRIVE &&
                res != FR_INVALID_OBJECT &&
                res != FR_TIMEOUT) {
                ff_rel_grant(fs->sobj);
        }
}
#endif



/*-----------------------------------------------------------------------*/
/* File shareing control functions                                       */
/*-----------------------------------------------------------------------*/
#if _FS_SHARE

static
FRESULT chk_lock (      /* Check if the file can be accessed */
        DIR* dj,                /* Directory object pointing the file to be checked */
        int acc                 /* Desired access (0:Read, 1:Write, 2:Delete/Rename) */
)
{
        UINT i, be;

        /* Search file semaphore table */
        for (i = be = 0; i < _FS_SHARE; i++) {
                if (Files[i].fs) {      /* Existing entry */
                        if (Files[i].fs == dj->fs &&            /* Check if the file matched with an open file */
                                Files[i].clu == dj->sclust &&
                                Files[i].idx == dj->index) break;
                } else {                        /* Blank entry */
                        be++;
                }
        }
        if (i == _FS_SHARE)     /* The file is not opened */
                return (be || acc == 2) ? FR_OK : FR_TOO_MANY_OPEN_FILES;       /* Is there a blank entry for new file? */

        /* The file has been opened. Reject any open against writing file and all write mode open */
        return (acc || Files[i].ctr == 0x100) ? FR_LOCKED : FR_OK;
}


static
int enq_lock (  /* Check if an entry is available for a new file */
        FATFS* fs       /* File system object */
)
{
        UINT i;

        for (i = 0; i < _FS_SHARE && Files[i].fs; i++) ;
        return (i == _FS_SHARE) ? 0 : 1;
}


static
UINT inc_lock ( /* Increment file open counter and returns its index (0:int error) */
        DIR* dj,        /* Directory object pointing the file to register or increment */
        int acc         /* Desired access mode (0:Read, !0:Write) */
)
{
        UINT i;


        for (i = 0; i < _FS_SHARE; i++) {       /* Find the file */
                if (Files[i].fs == dj->fs &&
                        Files[i].clu == dj->sclust &&
                        Files[i].idx == dj->index) break;
        }

        if (i == _FS_SHARE) {                           /* Not opened. Register it as new. */
                for (i = 0; i < _FS_SHARE && Files[i].fs; i++) ;
                if (i == _FS_SHARE) return 0;   /* No space to register (int err) */
                Files[i].fs = dj->fs;
                Files[i].clu = dj->sclust;
                Files[i].idx = dj->index;
                Files[i].ctr = 0;
        }

        if (acc && Files[i].ctr) return 0;      /* Access violation (int err) */

        Files[i].ctr = acc ? 0x100 : Files[i].ctr + 1;  /* Set semaphore value */

        return i + 1;
}


static
FRESULT dec_lock (      /* Decrement file open counter */
        UINT i                  /* Semaphore index */
)
{
        WORD n;
        FRESULT res;


        if (--i < _FS_SHARE) {
                n = Files[i].ctr;
                if (n == 0x100) n = 0;
                if (n) n--;
                Files[i].ctr = n;
                if (!n) Files[i].fs = 0;
                res = FR_OK;
        } else {
                res = FR_INT_ERR;
        }
        return res;
}


static
void clear_lock (       /* Clear lock entries of the volume */
        FATFS *fs
)
{
        UINT i;

        for (i = 0; i < _FS_SHARE; i++) {
                if (Files[i].fs == fs) Files[i].fs = 0;
        }
}
#endif



/*-----------------------------------------------------------------------*/
/* Change window offset                                                  */
/*-----------------------------------------------------------------------*/

static
FRESULT move_window (
        FATFS *fs,              /* File system object */
        DWORD sector    /* Sector number to make appearance in the fs->win[] */
)                                       /* Move to zero only writes back dirty window */
{
        DWORD wsect;


        wsect = fs->winsect;
        if (wsect != sector) {  /* Changed current window */
#if !_FS_READONLY
                if (fs->wflag) {        /* Write back dirty window if needed */
                        if (disk_write(fs->drv, fs->win, wsect, 1) != RES_OK)
                                return FR_DISK_ERR;
                        fs->wflag = 0;
                        if (wsect < (fs->fatbase + fs->fsize)) {        /* In FAT area */
                                BYTE nf;
                                for (nf = fs->n_fats; nf > 1; nf--) {   /* Reflect the change to all FAT copies */
                                        wsect += fs->fsize;
                                        disk_write(fs->drv, fs->win, wsect, 1);
                                }
                        }
                }
#endif
                if (sector) {
                        if (disk_read(fs->drv, fs->win, sector, 1) != RES_OK)
                                return FR_DISK_ERR;
                        fs->winsect = sector;
                }
        }

        return FR_OK;
}




/*-----------------------------------------------------------------------*/
/* Clean-up cached data                                                  */
/*-----------------------------------------------------------------------*/
#if !_FS_READONLY
static
FRESULT sync (  /* FR_OK: successful, FR_DISK_ERR: failed */
        FATFS *fs       /* File system object */
)
{
        FRESULT res;


        res = move_window(fs, 0);
        if (res == FR_OK) {
                /* Update FSInfo sector if needed */
                if (fs->fs_type == FS_FAT32 && fs->fsi_flag) {
                        fs->winsect = 0;
                        mem_set(fs->win, 0, 512);
                        ST_WORD(fs->win+BS_55AA, 0xAA55);
                        ST_DWORD(fs->win+FSI_LeadSig, 0x41615252);
                        ST_DWORD(fs->win+FSI_StrucSig, 0x61417272);
                        ST_DWORD(fs->win+FSI_Free_Count, fs->free_clust);
                        ST_DWORD(fs->win+FSI_Nxt_Free, fs->last_clust);
                        disk_write(fs->drv, fs->win, fs->fsi_sector, 1);
                        fs->fsi_flag = 0;
                }
                /* Make sure that no pending write process in the physical drive */
                if (disk_ioctl(fs->drv, CTRL_SYNC, (void*)0) != RES_OK)
                        res = FR_DISK_ERR;
        }

        return res;
}
#endif




/*-----------------------------------------------------------------------*/
/* Get sector# from cluster#                                             */
/*-----------------------------------------------------------------------*/


DWORD clust2sect (      /* !=0: Sector number, 0: Failed - invalid cluster# */
        FATFS *fs,              /* File system object */
        DWORD clst              /* Cluster# to be converted */
)
{
        clst -= 2;
        if (clst >= (fs->n_fatent - 2)) return 0;               /* Invalid cluster# */
        return clst * fs->csize + fs->database;
}




/*-----------------------------------------------------------------------*/
/* FAT access - Read value of a FAT entry                                */
/*-----------------------------------------------------------------------*/


DWORD get_fat ( /* 0xFFFFFFFF:Disk error, 1:Internal error, Else:Cluster status */
        FATFS *fs,      /* File system object */
        DWORD clst      /* Cluster# to get the link information */
)
{
        UINT wc, bc;
        BYTE *p;


        if (clst < 2 || clst >= fs->n_fatent)   /* Chack range */
                return 1;

        switch (fs->fs_type) {
        case FS_FAT12 :
                bc = (UINT)clst; bc += bc / 2;
                if (move_window(fs, fs->fatbase + (bc / SS(fs)))) break;
                wc = fs->win[bc % SS(fs)]; bc++;
                if (move_window(fs, fs->fatbase + (bc / SS(fs)))) break;
                wc |= fs->win[bc % SS(fs)] << 8;
                return (clst & 1) ? (wc >> 4) : (wc & 0xFFF);

        case FS_FAT16 :
                if (move_window(fs, fs->fatbase + (clst / (SS(fs) / 2)))) break;
                p = &fs->win[clst * 2 % SS(fs)];
                return LD_WORD(p);

        case FS_FAT32 :
                if (move_window(fs, fs->fatbase + (clst / (SS(fs) / 4)))) break;
                p = &fs->win[clst * 4 % SS(fs)];
                return LD_DWORD(p) & 0x0FFFFFFF;
        }

        return 0xFFFFFFFF;      /* An error occurred at the disk I/O layer */
}




/*-----------------------------------------------------------------------*/
/* FAT access - Change value of a FAT entry                              */
/*-----------------------------------------------------------------------*/
#if !_FS_READONLY

FRESULT put_fat (
        FATFS *fs,      /* File system object */
        DWORD clst,     /* Cluster# to be changed in range of 2 to fs->n_fatent - 1 */
        DWORD val       /* New value to mark the cluster */
)
{
        UINT bc;
        BYTE *p;
        FRESULT res;


        if (clst < 2 || clst >= fs->n_fatent) { /* Check range */
                res = FR_INT_ERR;

        } else {
                switch (fs->fs_type) {
                case FS_FAT12 :
                        bc = clst; bc += bc / 2;
                        res = move_window(fs, fs->fatbase + (bc / SS(fs)));
                        if (res != FR_OK) break;
                        p = &fs->win[bc % SS(fs)];
                        *p = (clst & 1) ? ((*p & 0x0F) | ((BYTE)val << 4)) : (BYTE)val;
                        bc++;
                        fs->wflag = 1;
                        res = move_window(fs, fs->fatbase + (bc / SS(fs)));
                        if (res != FR_OK) break;
                        p = &fs->win[bc % SS(fs)];
                        *p = (clst & 1) ? (BYTE)(val >> 4) : ((*p & 0xF0) | ((BYTE)(val >> 8) & 0x0F));
                        break;

                case FS_FAT16 :
                        res = move_window(fs, fs->fatbase + (clst / (SS(fs) / 2)));
                        if (res != FR_OK) break;
                        p = &fs->win[clst * 2 % SS(fs)];
                        ST_WORD(p, (WORD)val);
                        break;

                case FS_FAT32 :
                        res = move_window(fs, fs->fatbase + (clst / (SS(fs) / 4)));
                        if (res != FR_OK) break;
                        p = &fs->win[clst * 4 % SS(fs)];
                        val |= LD_DWORD(p) & 0xF0000000;
                        ST_DWORD(p, val);
                        break;

                default :
                        res = FR_INT_ERR;
                }
                fs->wflag = 1;
        }

        return res;
}
#endif /* !_FS_READONLY */




/*-----------------------------------------------------------------------*/
/* FAT handling - Remove a cluster chain                                 */
/*-----------------------------------------------------------------------*/
#if !_FS_READONLY
static
FRESULT remove_chain (
        FATFS *fs,                      /* File system object */
        DWORD clst                      /* Cluster# to remove a chain from */
)
{
        FRESULT res;
        DWORD nxt;
#if _USE_ERASE
        DWORD scl = clst, ecl = clst, resion[2];
#endif

        if (clst < 2 || clst >= fs->n_fatent) { /* Check range */
                res = FR_INT_ERR;

        } else {
                res = FR_OK;
                while (clst < fs->n_fatent) {                   /* Not a last link? */
                        nxt = get_fat(fs, clst);                        /* Get cluster status */
                        if (nxt == 0) break;                            /* Empty cluster? */
                        if (nxt == 1) { res = FR_INT_ERR; break; }      /* Internal error? */
                        if (nxt == 0xFFFFFFFF) { res = FR_DISK_ERR; break; }    /* Disk error? */
                        res = put_fat(fs, clst, 0);                     /* Mark the cluster "empty" */
                        if (res != FR_OK) break;
                        if (fs->free_clust != 0xFFFFFFFF) {     /* Update FSInfo */
                                fs->free_clust++;
                                fs->fsi_flag = 1;
                        }
#if _USE_ERASE
                        if (ecl + 1 == nxt) {   /* Next cluster is contiguous */
                                ecl = nxt;
                        } else {                                /* End of contiguous clusters */ 
                                resion[0] = clust2sect(fs, scl);                                        /* Start sector */
                                resion[1] = clust2sect(fs, ecl) + fs->csize - 1;        /* End sector */
                                disk_ioctl(fs->drv, CTRL_ERASE_SECTOR, resion);         /* Erase the block */
                                scl = ecl = nxt;
                        }
#endif
                        clst = nxt;     /* Next cluster */
                }
        }

        return res;
}
#endif




/*-----------------------------------------------------------------------*/
/* FAT handling - Stretch or Create a cluster chain                      */
/*-----------------------------------------------------------------------*/
#if !_FS_READONLY
static
DWORD create_chain (    /* 0:No free cluster, 1:Internal error, 0xFFFFFFFF:Disk error, >=2:New cluster# */
        FATFS *fs,                      /* File system object */
        DWORD clst                      /* Cluster# to stretch. 0 means create a new chain. */
)
{
        DWORD cs, ncl, scl;
        FRESULT res;


        if (clst == 0) {                /* Create a new chain */
                scl = fs->last_clust;                   /* Get suggested start point */
                if (!scl || scl >= fs->n_fatent) scl = 1;
        }
        else {                                  /* Stretch the current chain */
                cs = get_fat(fs, clst);                 /* Check the cluster status */
                if (cs < 2) return 1;                   /* It is an invalid cluster */
                if (cs < fs->n_fatent) return cs;       /* It is already followed by next cluster */
                scl = clst;
        }

        ncl = scl;                              /* Start cluster */
        for (;;) {
                ncl++;                                                  /* Next cluster */
                if (ncl >= fs->n_fatent) {              /* Wrap around */
                        ncl = 2;
                        if (ncl > scl) return 0;        /* No free cluster */
                }
                cs = get_fat(fs, ncl);                  /* Get the cluster status */
                if (cs == 0) break;                             /* Found a free cluster */
                if (cs == 0xFFFFFFFF || cs == 1)/* An error occurred */
                        return cs;
                if (ncl == scl) return 0;               /* No free cluster */
        }

        res = put_fat(fs, ncl, 0x0FFFFFFF);     /* Mark the new cluster "last link" */
        if (res == FR_OK && clst != 0) {
                res = put_fat(fs, clst, ncl);   /* Link it to the previous one if needed */
        }
        if (res == FR_OK) {
                fs->last_clust = ncl;                   /* Update FSINFO */
                if (fs->free_clust != 0xFFFFFFFF) {
                        fs->free_clust--;
                        fs->fsi_flag = 1;
                }
        } else {
                ncl = (res == FR_DISK_ERR) ? 0xFFFFFFFF : 1;
        }

        return ncl;             /* Return new cluster number or error code */
}
#endif /* !_FS_READONLY */




/*-----------------------------------------------------------------------*/
/* Directory handling - Set directory index                              */
/*-----------------------------------------------------------------------*/

static
FRESULT dir_sdi (
        DIR *dj,                /* Pointer to directory object */
        WORD idx                /* Directory index number */
)
{
        DWORD clst;
        WORD ic;


        dj->index = idx;
        clst = dj->sclust;
        if (clst == 1 || clst >= dj->fs->n_fatent)      /* Check start cluster range */
                return FR_INT_ERR;
        if (!clst && dj->fs->fs_type == FS_FAT32)       /* Replace cluster# 0 with root cluster# if in FAT32 */
                clst = dj->fs->dirbase;

        if (clst == 0) {        /* Static table (root-dir in FAT12/16) */
                dj->clust = clst;
                if (idx >= dj->fs->n_rootdir)           /* Index is out of range */
                        return FR_INT_ERR;
                dj->sect = dj->fs->dirbase + idx / (SS(dj->fs) / 32);   /* Sector# */
        }
        else {                          /* Dynamic table (sub-dirs or root-dir in FAT32) */
                ic = SS(dj->fs) / 32 * dj->fs->csize;   /* Entries per cluster */
                while (idx >= ic) {     /* Follow cluster chain */
                        clst = get_fat(dj->fs, clst);                           /* Get next cluster */
                        if (clst == 0xFFFFFFFF) return FR_DISK_ERR;     /* Disk error */
                        if (clst < 2 || clst >= dj->fs->n_fatent)       /* Reached to end of table or int error */
                                return FR_INT_ERR;
                        idx -= ic;
                }
                dj->clust = clst;
                dj->sect = clust2sect(dj->fs, clst) + idx / (SS(dj->fs) / 32);  /* Sector# */
        }

        dj->dir = dj->fs->win + (idx % (SS(dj->fs) / 32)) * 32; /* Ptr to the entry in the sector */

        return FR_OK;   /* Seek succeeded */
}




/*-----------------------------------------------------------------------*/
/* Directory handling - Move directory index next                        */
/*-----------------------------------------------------------------------*/

static
FRESULT dir_next (      /* FR_OK:Succeeded, FR_NO_FILE:End of table, FR_DENIED:EOT and could not stretch */
        DIR *dj,                /* Pointer to directory object */
        int stretch             /* 0: Do not stretch table, 1: Stretch table if needed */
)
{
        DWORD clst;
        WORD i;


        i = dj->index + 1;
        if (!i || !dj->sect)    /* Report EOT when index has reached 65535 */
                return FR_NO_FILE;

        if (!(i % (SS(dj->fs) / 32))) { /* Sector changed? */
                dj->sect++;                                     /* Next sector */

                if (dj->clust == 0) {   /* Static table */
                        if (i >= dj->fs->n_rootdir)     /* Report EOT when end of table */
                                return FR_NO_FILE;
                }
                else {                                  /* Dynamic table */
                        if (((i / (SS(dj->fs) / 32)) & (dj->fs->csize - 1)) == 0) {     /* Cluster changed? */
                                clst = get_fat(dj->fs, dj->clust);                              /* Get next cluster */
                                if (clst <= 1) return FR_INT_ERR;
                                if (clst == 0xFFFFFFFF) return FR_DISK_ERR;
                                if (clst >= dj->fs->n_fatent) {                                 /* When it reached end of dynamic table */
#if !_FS_READONLY
                                        BYTE c;
                                        if (!stretch) return FR_NO_FILE;                        /* When do not stretch, report EOT */
                                        clst = create_chain(dj->fs, dj->clust);         /* Stretch cluster chain */
                                        if (clst == 0) return FR_DENIED;                        /* No free cluster */
                                        if (clst == 1) return FR_INT_ERR;
                                        if (clst == 0xFFFFFFFF) return FR_DISK_ERR;
                                        /* Clean-up stretched table */
                                        if (move_window(dj->fs, 0)) return FR_DISK_ERR; /* Flush active window */
                                        mem_set(dj->fs->win, 0, SS(dj->fs));                    /* Clear window buffer */
                                        dj->fs->winsect = clust2sect(dj->fs, clst);     /* Cluster start sector */
                                        for (c = 0; c < dj->fs->csize; c++) {           /* Fill the new cluster with 0 */
                                                dj->fs->wflag = 1;
                                                if (move_window(dj->fs, 0)) return FR_DISK_ERR;
                                                dj->fs->winsect++;
                                        }
                                        dj->fs->winsect -= c;                                           /* Rewind window address */
#else
                                        return FR_NO_FILE;                      /* Report EOT */
#endif
                                }
                                dj->clust = clst;                               /* Initialize data for new cluster */
                                dj->sect = clust2sect(dj->fs, clst);
                        }
                }
        }

        dj->index = i;
        dj->dir = dj->fs->win + (i % (SS(dj->fs) / 32)) * 32;

        return FR_OK;
}




/*-----------------------------------------------------------------------*/
/* LFN handling - Test/Pick/Fit an LFN segment from/to directory entry   */
/*-----------------------------------------------------------------------*/
#if _USE_LFN
static
const BYTE LfnOfs[] = {1,3,5,7,9,14,16,18,20,22,24,28,30};      /* Offset of LFN chars in the directory entry */


static
int cmp_lfn (                   /* 1:Matched, 0:Not matched */
        WCHAR *lfnbuf,          /* Pointer to the LFN to be compared */
        BYTE *dir                       /* Pointer to the directory entry containing a part of LFN */
)
{
        UINT i, s;
        WCHAR wc, uc;


        i = ((dir[LDIR_Ord] & 0xBF) - 1) * 13;  /* Get offset in the LFN buffer */
        s = 0; wc = 1;
        do {
                uc = LD_WORD(dir+LfnOfs[s]);    /* Pick an LFN character from the entry */
                if (wc) {       /* Last char has not been processed */
                        wc = ff_wtoupper(uc);           /* Convert it to upper case */
                        if (i >= _MAX_LFN || wc != ff_wtoupper(lfnbuf[i++]))    /* Compare it */
                                return 0;                               /* Not matched */
                } else {
                        if (uc != 0xFFFF) return 0;     /* Check filler */
                }
        } while (++s < 13);                             /* Repeat until all chars in the entry are checked */

        if ((dir[LDIR_Ord] & 0x40) && wc && lfnbuf[i])  /* Last segment matched but different length */
                return 0;

        return 1;                                               /* The part of LFN matched */
}



static
int pick_lfn (                  /* 1:Succeeded, 0:Buffer overflow */
        WCHAR *lfnbuf,          /* Pointer to the Unicode-LFN buffer */
        BYTE *dir                       /* Pointer to the directory entry */
)
{
        UINT i, s;
        WCHAR wc, uc;


        i = ((dir[LDIR_Ord] & 0x3F) - 1) * 13;  /* Offset in the LFN buffer */

        s = 0; wc = 1;
        do {
                uc = LD_WORD(dir+LfnOfs[s]);            /* Pick an LFN character from the entry */
                if (wc) {       /* Last char has not been processed */
                        if (i >= _MAX_LFN) return 0;    /* Buffer overflow? */
                        lfnbuf[i++] = wc = uc;                  /* Store it */
                } else {
                        if (uc != 0xFFFF) return 0;             /* Check filler */
                }
        } while (++s < 13);                                             /* Read all character in the entry */

        if (dir[LDIR_Ord] & 0x40) {                             /* Put terminator if it is the last LFN part */
                if (i >= _MAX_LFN) return 0;            /* Buffer overflow? */
                lfnbuf[i] = 0;
        }

        return 1;
}


#if !_FS_READONLY
static
void fit_lfn (
        const WCHAR *lfnbuf,    /* Pointer to the LFN buffer */
        BYTE *dir,                              /* Pointer to the directory entry */
        BYTE ord,                               /* LFN order (1-20) */
        BYTE sum                                /* SFN sum */
)
{
        UINT i, s;
        WCHAR wc;


        dir[LDIR_Chksum] = sum;                 /* Set check sum */
        dir[LDIR_Attr] = AM_LFN;                /* Set attribute. LFN entry */
        dir[LDIR_Type] = 0;
        ST_WORD(dir+LDIR_FstClusLO, 0);

        i = (ord - 1) * 13;                             /* Get offset in the LFN buffer */
        s = wc = 0;
        do {
                if (wc != 0xFFFF) wc = lfnbuf[i++];     /* Get an effective char */
                ST_WORD(dir+LfnOfs[s], wc);     /* Put it */
                if (!wc) wc = 0xFFFF;           /* Padding chars following last char */
        } while (++s < 13);
        if (wc == 0xFFFF || !lfnbuf[i]) ord |= 0x40;    /* Bottom LFN part is the start of LFN sequence */
        dir[LDIR_Ord] = ord;                    /* Set the LFN order */
}

#endif
#endif



/*-----------------------------------------------------------------------*/
/* Create numbered name                                                  */
/*-----------------------------------------------------------------------*/
#if _USE_LFN
void gen_numname (
        BYTE *dst,                      /* Pointer to generated SFN */
        const BYTE *src,        /* Pointer to source SFN to be modified */
        const WCHAR *lfn,       /* Pointer to LFN */
        WORD seq                        /* Sequence number */
)
{
        BYTE ns[8], c;
        UINT i, j;


        mem_cpy(dst, src, 11);

        if (seq > 5) {  /* On many collisions, generate a hash number instead of sequential number */
                do seq = (seq >> 1) + (seq << 15) + (WORD)*lfn++; while (*lfn);
        }

        /* itoa */
        i = 7;
        do {
                c = (seq % 16) + '0';
                if (c > '9') c += 7;
                ns[i--] = c;
                seq /= 16;
        } while (seq);
        ns[i] = '~';

        /* Append the number */
        for (j = 0; j < i && dst[j] != ' '; j++) {
                if (IsDBCS1(dst[j])) {
                        if (j == i - 1) break;
                        j++;
                }
        }
        do {
                dst[j++] = (i < 8) ? ns[i++] : ' ';
        } while (j < 8);
}
#endif




/*-----------------------------------------------------------------------*/
/* Calculate sum of an SFN                                               */
/*-----------------------------------------------------------------------*/
#if _USE_LFN
static
BYTE sum_sfn (
        const BYTE *dir         /* Ptr to directory entry */
)
{
        BYTE sum = 0;
        UINT n = 11;

        do sum = (sum >> 1) + (sum << 7) + *dir++; while (--n);
        return sum;
}
#endif




/*-----------------------------------------------------------------------*/
/* Directory handling - Find an object in the directory                  */
/*-----------------------------------------------------------------------*/

static
FRESULT dir_find (
        DIR *dj                 /* Pointer to the directory object linked to the file name */
)
{
        FRESULT res;
        BYTE c, *dir;
#if _USE_LFN
        BYTE a, ord, sum;
#endif

        res = dir_sdi(dj, 0);                   /* Rewind directory object */
        if (res != FR_OK) return res;

#if _USE_LFN
        ord = sum = 0xFF;
#endif
        do {
                res = move_window(dj->fs, dj->sect);
                if (res != FR_OK) break;
                dir = dj->dir;                                  /* Ptr to the directory entry of current index */
                c = dir[DIR_Name];
                if (c == 0) { res = FR_NO_FILE; break; }        /* Reached to end of table */
#if _USE_LFN    /* LFN configuration */
                a = dir[DIR_Attr] & AM_MASK;
                if (c == 0xE5 || ((a & AM_VOL) && a != AM_LFN)) {       /* An entry without valid data */
                        ord = 0xFF;
                } else {
                        if (a == AM_LFN) {                      /* An LFN entry is found */
                                if (dj->lfn) {
                                        if (c & 0x40) {         /* Is it start of LFN sequence? */
                                                sum = dir[LDIR_Chksum];
                                                c &= 0xBF; ord = c;     /* LFN start order */
                                                dj->lfn_idx = dj->index;
                                        }
                                        /* Check validity of the LFN entry and compare it with given name */
                                        ord = (c == ord && sum == dir[LDIR_Chksum] && cmp_lfn(dj->lfn, dir)) ? ord - 1 : 0xFF;
                                }
                        } else {                                        /* An SFN entry is found */
                                if (!ord && sum == sum_sfn(dir)) break; /* LFN matched? */
                                ord = 0xFF; dj->lfn_idx = 0xFFFF;       /* Reset LFN sequence */
                                if (!(dj->fn[NS] & NS_LOSS) && !mem_cmp(dir, dj->fn, 11)) break;        /* SFN matched? */
                        }
                }
#else           /* Non LFN configuration */
                if (!(dir[DIR_Attr] & AM_VOL) && !mem_cmp(dir, dj->fn, 11)) /* Is it a valid entry? */
                        break;
#endif
                res = dir_next(dj, 0);          /* Next entry */
        } while (res == FR_OK);

        return res;
}




/*-----------------------------------------------------------------------*/
/* Read an object from the directory                                     */
/*-----------------------------------------------------------------------*/
#if _FS_MINIMIZE <= 1
static
FRESULT dir_read (
        DIR *dj                 /* Pointer to the directory object that pointing the entry to be read */
)
{
        FRESULT res;
        BYTE c, *dir;
#if _USE_LFN
        BYTE a, ord = 0xFF, sum = 0xFF;
#endif

        res = FR_NO_FILE;
        while (dj->sect) {
                res = move_window(dj->fs, dj->sect);
                if (res != FR_OK) break;
                dir = dj->dir;                                  /* Ptr to the directory entry of current index */
                c = dir[DIR_Name];
                if (c == 0) { res = FR_NO_FILE; break; }        /* Reached to end of table */
#if _USE_LFN    /* LFN configuration */
                a = dir[DIR_Attr] & AM_MASK;
                if (c == 0xE5 || (!_FS_RPATH && c == '.') || ((a & AM_VOL) && a != AM_LFN)) {   /* An entry without valid data */
                        ord = 0xFF;
                } else {
                        if (a == AM_LFN) {                      /* An LFN entry is found */
                                if (c & 0x40) {                 /* Is it start of LFN sequence? */
                                        sum = dir[LDIR_Chksum];
                                        c &= 0xBF; ord = c;
                                        dj->lfn_idx = dj->index;
                                }
                                /* Check LFN validity and capture it */
                                ord = (c == ord && sum == dir[LDIR_Chksum] && pick_lfn(dj->lfn, dir)) ? ord - 1 : 0xFF;
                        } else {                                        /* An SFN entry is found */
                                if (ord || sum != sum_sfn(dir)) /* Is there a valid LFN? */
                                        dj->lfn_idx = 0xFFFF;           /* It has no LFN. */
                                break;
                        }
                }
#else           /* Non LFN configuration */
                if (c != 0xE5 && (_FS_RPATH || c != '.') && !(dir[DIR_Attr] & AM_VOL))  /* Is it a valid entry? */
                        break;
#endif
                res = dir_next(dj, 0);                          /* Next entry */
                if (res != FR_OK) break;
        }

        if (res != FR_OK) dj->sect = 0;

        return res;
}
#endif



/*-----------------------------------------------------------------------*/
/* Register an object to the directory                                   */
/*-----------------------------------------------------------------------*/
#if !_FS_READONLY
static
FRESULT dir_register (  /* FR_OK:Successful, FR_DENIED:No free entry or too many SFN collision, FR_DISK_ERR:Disk error */
        DIR *dj                         /* Target directory with object name to be created */
)
{
        FRESULT res;
        BYTE c, *dir;
#if _USE_LFN    /* LFN configuration */
        WORD n, ne, is;
        BYTE sn[12], *fn, sum;
        WCHAR *lfn;


        fn = dj->fn; lfn = dj->lfn;
        mem_cpy(sn, fn, 12);

        if (_FS_RPATH && (sn[NS] & NS_DOT))             /* Cannot create dot entry */
                return FR_INVALID_NAME;

        if (sn[NS] & NS_LOSS) {                 /* When LFN is out of 8.3 format, generate a numbered name */
                fn[NS] = 0; dj->lfn = 0;                        /* Find only SFN */
                for (n = 1; n < 100; n++) {
                        gen_numname(fn, sn, lfn, n);    /* Generate a numbered name */
                        res = dir_find(dj);                             /* Check if the name collides with existing SFN */
                        if (res != FR_OK) break;
                }
                if (n == 100) return FR_DENIED;         /* Abort if too many collisions */
                if (res != FR_NO_FILE) return res;      /* Abort if the result is other than 'not collided' */
                fn[NS] = sn[NS]; dj->lfn = lfn;
        }

        if (sn[NS] & NS_LFN) {                  /* When LFN is to be created, reserve an SFN + LFN entries. */
                for (ne = 0; lfn[ne]; ne++) ;
                ne = (ne + 25) / 13;
        } else {                                                /* Otherwise reserve only an SFN entry. */
                ne = 1;
        }

        /* Reserve contiguous entries */
        res = dir_sdi(dj, 0);
        if (res != FR_OK) return res;
        n = is = 0;
        do {
                res = move_window(dj->fs, dj->sect);
                if (res != FR_OK) break;
                c = *dj->dir;                           /* Check the entry status */
                if (c == 0xE5 || c == 0) {      /* Is it a blank entry? */
                        if (n == 0) is = dj->index;     /* First index of the contiguous entry */
                        if (++n == ne) break;   /* A contiguous entry that required count is found */
                } else {
                        n = 0;                                  /* Not a blank entry. Restart to search */
                }
                res = dir_next(dj, 1);          /* Next entry with table stretch */
        } while (res == FR_OK);

        if (res == FR_OK && ne > 1) {   /* Initialize LFN entry if needed */
                res = dir_sdi(dj, is);
                if (res == FR_OK) {
                        sum = sum_sfn(dj->fn);  /* Sum of the SFN tied to the LFN */
                        ne--;
                        do {                                    /* Store LFN entries in bottom first */
                                res = move_window(dj->fs, dj->sect);
                                if (res != FR_OK) break;
                                fit_lfn(dj->lfn, dj->dir, (BYTE)ne, sum);
                                dj->fs->wflag = 1;
                                res = dir_next(dj, 0);  /* Next entry */
                        } while (res == FR_OK && --ne);
                }
        }

#else   /* Non LFN configuration */
        res = dir_sdi(dj, 0);
        if (res == FR_OK) {
                do {    /* Find a blank entry for the SFN */
                        res = move_window(dj->fs, dj->sect);
                        if (res != FR_OK) break;
                        c = *dj->dir;
                        if (c == 0xE5 || c == 0) break; /* Is it a blank entry? */
                        res = dir_next(dj, 1);                  /* Next entry with table stretch */
                } while (res == FR_OK);
        }
#endif

        if (res == FR_OK) {             /* Initialize the SFN entry */
                res = move_window(dj->fs, dj->sect);
                if (res == FR_OK) {
                        dir = dj->dir;
                        mem_set(dir, 0, 32);            /* Clean the entry */
                        mem_cpy(dir, dj->fn, 11);       /* Put SFN */
#if _USE_LFN
                        dir[DIR_NTres] = *(dj->fn+NS) & (NS_BODY | NS_EXT);     /* Put NT flag */
#endif
                        dj->fs->wflag = 1;
                }
        }

        return res;
}
#endif /* !_FS_READONLY */




/*-----------------------------------------------------------------------*/
/* Remove an object from the directory                                   */
/*-----------------------------------------------------------------------*/
#if !_FS_READONLY && !_FS_MINIMIZE
static
FRESULT dir_remove (    /* FR_OK: Successful, FR_DISK_ERR: A disk error */
        DIR *dj                         /* Directory object pointing the entry to be removed */
)
{
        FRESULT res;
#if _USE_LFN    /* LFN configuration */
        WORD i;

        i = dj->index;  /* SFN index */
        res = dir_sdi(dj, (WORD)((dj->lfn_idx == 0xFFFF) ? i : dj->lfn_idx));   /* Goto the SFN or top of the LFN entries */
        if (res == FR_OK) {
                do {
                        res = move_window(dj->fs, dj->sect);
                        if (res != FR_OK) break;
                        *dj->dir = 0xE5;                        /* Mark the entry "deleted" */
                        dj->fs->wflag = 1;
                        if (dj->index >= i) break;      /* When reached SFN, all entries of the object has been deleted. */
                        res = dir_next(dj, 0);          /* Next entry */
                } while (res == FR_OK);
                if (res == FR_NO_FILE) res = FR_INT_ERR;
        }

#else                   /* Non LFN configuration */
        res = dir_sdi(dj, dj->index);
        if (res == FR_OK) {
                res = move_window(dj->fs, dj->sect);
                if (res == FR_OK) {
                        *dj->dir = 0xE5;                        /* Mark the entry "deleted" */
                        dj->fs->wflag = 1;
                }
        }
#endif

        return res;
}
#endif /* !_FS_READONLY */




/*-----------------------------------------------------------------------*/
/* Pick a segment and create the object name in directory form           */
/*-----------------------------------------------------------------------*/

static
FRESULT create_name (
        DIR *dj,                        /* Pointer to the directory object */
        const TCHAR **path      /* Pointer to pointer to the segment in the path string */
)
{
#ifdef _EXCVT
        static const BYTE excvt[] = _EXCVT;     /* Upper conversion table for extended chars */
#endif

#if _USE_LFN    /* LFN configuration */
        BYTE b, cf;
        WCHAR w, *lfn;
        UINT i, ni, si, di;
        const TCHAR *p;

        /* Create LFN in Unicode */
        si = di = 0;
        p = *path;
        lfn = dj->lfn;
        for (;;) {
                w = p[si++];                                    /* Get a character */
                if (w < ' ' || w == '/' || w == '\\') break;    /* Break on end of segment */
                if (di >= _MAX_LFN)                             /* Reject too long name */
                        return FR_INVALID_NAME;
#if !_LFN_UNICODE
                w &= 0xFF;
                if (IsDBCS1(w)) {                               /* Check if it is a DBC 1st byte (always false on SBCS cfg) */
                        b = (BYTE)p[si++];                      /* Get 2nd byte */
                        if (!IsDBCS2(b))
                                return FR_INVALID_NAME; /* Reject invalid sequence */
                        w = (w << 8) + b;                       /* Create a DBC */
                }
                w = ff_convert(w, 1);                   /* Convert ANSI/OEM to Unicode */
                if (!w) return FR_INVALID_NAME; /* Reject invalid code */
#endif
                if (w < 0x80 && chk_chr("\"*:<>\?|\x7F", w)) /* Reject illegal chars for LFN */
                        return FR_INVALID_NAME;
                lfn[di++] = w;                                  /* Store the Unicode char */
        }
        *path = &p[si];                                         /* Return pointer to the next segment */
        cf = (w < ' ') ? NS_LAST : 0;           /* Set last segment flag if end of path */
#if _FS_RPATH
        if ((di == 1 && lfn[di-1] == '.') || /* Is this a dot entry? */
                (di == 2 && lfn[di-1] == '.' && lfn[di-2] == '.')) {
                lfn[di] = 0;
                for (i = 0; i < 11; i++)
                        dj->fn[i] = (i < di) ? '.' : ' ';
                dj->fn[i] = cf | NS_DOT;                /* This is a dot entry */
                return FR_OK;
        }
#endif
        while (di) {                                            /* Strip trailing spaces and dots */
                w = lfn[di-1];
                if (w != ' ' && w != '.') break;
                di--;
        }
        if (!di) return FR_INVALID_NAME;        /* Reject nul string */

        lfn[di] = 0;                                            /* LFN is created */

        /* Create SFN in directory form */
        mem_set(dj->fn, ' ', 11);
        for (si = 0; lfn[si] == ' ' || lfn[si] == '.'; si++) ;  /* Strip leading spaces and dots */
        if (si) cf |= NS_LOSS | NS_LFN;
        while (di && lfn[di - 1] != '.') di--;  /* Find extension (di<=si: no extension) */

        b = i = 0; ni = 8;
        for (;;) {
                w = lfn[si++];                                  /* Get an LFN char */
                if (!w) break;                                  /* Break on end of the LFN */
                if (w == ' ' || (w == '.' && si != di)) {       /* Remove spaces and dots */
                        cf |= NS_LOSS | NS_LFN; continue;
                }

                if (i >= ni || si == di) {              /* Extension or end of SFN */
                        if (ni == 11) {                         /* Long extension */
                                cf |= NS_LOSS | NS_LFN; break;
                        }
                        if (si != di) cf |= NS_LOSS | NS_LFN;   /* Out of 8.3 format */
                        if (si > di) break;                     /* No extension */
                        si = di; i = 8; ni = 11;        /* Enter extension section */
                        b <<= 2; continue;
                }

                if (w >= 0x80) {                                /* Non ASCII char */
#ifdef _EXCVT
                        w = ff_convert(w, 0);           /* Unicode -> OEM code */
                        if (w) w = excvt[w - 0x80];     /* Convert extended char to upper (SBCS) */
#else
                        w = ff_convert(ff_wtoupper(w), 0);      /* Upper converted Unicode -> OEM code */
#endif
                        cf |= NS_LFN;                           /* Force create LFN entry */
                }

                if (_DF1S && w >= 0x100) {              /* Double byte char (always false on SBCS cfg) */
                        if (i >= ni - 1) {
                                cf |= NS_LOSS | NS_LFN; i = ni; continue;
                        }
                        dj->fn[i++] = (BYTE)(w >> 8);
                } else {                                                /* Single byte char */
                        if (!w || chk_chr("+,;=[]", w)) {       /* Replace illegal chars for SFN */
                                w = '_'; cf |= NS_LOSS | NS_LFN;/* Lossy conversion */
                        } else {
                                if (IsUpper(w)) {               /* ASCII large capital */
                                        b |= 2;
                                } else {
                                        if (IsLower(w)) {       /* ASCII small capital */
                                                b |= 1; w -= 0x20;
                                        }
                                }
                        }
                }
                dj->fn[i++] = (BYTE)w;
        }

        if (dj->fn[0] == 0xE5) dj->fn[0] = 0x05;        /* If the first char collides with deleted mark, replace it with 0x05 */

        if (ni == 8) b <<= 2;
        if ((b & 0x0C) == 0x0C || (b & 0x03) == 0x03)   /* Create LFN entry when there are composite capitals */
                cf |= NS_LFN;
        if (!(cf & NS_LFN)) {                                           /* When LFN is in 8.3 format without extended char, NT flags are created */
                if ((b & 0x03) == 0x01) cf |= NS_EXT;   /* NT flag (Extension has only small capital) */
                if ((b & 0x0C) == 0x04) cf |= NS_BODY;  /* NT flag (Filename has only small capital) */
        }

        dj->fn[NS] = cf;        /* SFN is created */

        return FR_OK;


#else   /* Non-LFN configuration */
        BYTE b, c, d, *sfn;
        UINT ni, si, i;
        const char *p;

        /* Create file name in directory form */
        sfn = dj->fn;
        mem_set(sfn, ' ', 11);
        si = i = b = 0; ni = 8;
        p = *path;
#if _FS_RPATH
        if (p[si] == '.') { /* Is this a dot entry? */
                for (;;) {
                        c = (BYTE)p[si++];
                        if (c != '.' || si >= 3) break;
                        sfn[i++] = c;
                }
                if (c != '/' && c != '\\' && c > ' ') return FR_INVALID_NAME;
                *path = &p[si];                                                                 /* Return pointer to the next segment */
                sfn[NS] = (c <= ' ') ? NS_LAST | NS_DOT : NS_DOT;       /* Set last segment flag if end of path */
                return FR_OK;
        }
#endif
        for (;;) {
                c = (BYTE)p[si++];
                if (c <= ' ' || c == '/' || c == '\\') break;   /* Break on end of segment */
                if (c == '.' || i >= ni) {
                        if (ni != 8 || c != '.') return FR_INVALID_NAME;
                        i = 8; ni = 11;
                        b <<= 2; continue;
                }
                if (c >= 0x80) {                                /* Extended char? */
                        b |= 3;                                         /* Eliminate NT flag */
#ifdef _EXCVT
                        c = excvt[c-0x80];                      /* Upper conversion (SBCS) */
#else
#if !_DF1S      /* ASCII only cfg */
                        return FR_INVALID_NAME;
#endif
#endif
                }
                if (IsDBCS1(c)) {                               /* Check if it is a DBC 1st byte (always false on SBCS cfg) */
                        d = (BYTE)p[si++];                      /* Get 2nd byte */
                        if (!IsDBCS2(d) || i >= ni - 1) /* Reject invalid DBC */
                                return FR_INVALID_NAME;
                        sfn[i++] = c;
                        sfn[i++] = d;
                } else {                                                /* Single byte code */
                        if (chk_chr("\"*+,:;<=>\?[]|\x7F", c))  /* Reject illegal chrs for SFN */
                                return FR_INVALID_NAME;
                        if (IsUpper(c)) {                       /* ASCII large capital? */
                                b |= 2;
                        } else {
                                if (IsLower(c)) {               /* ASCII small capital? */
                                        b |= 1; c -= 0x20;
                                }
                        }
                        sfn[i++] = c;
                }
        }
        *path = &p[si];                                         /* Return pointer to the next segment */
        c = (c <= ' ') ? NS_LAST : 0;           /* Set last segment flag if end of path */

        if (!i) return FR_INVALID_NAME;         /* Reject nul string */
        if (sfn[0] == 0xE5) sfn[0] = 0x05;      /* When first char collides with 0xE5, replace it with 0x05 */

        if (ni == 8) b <<= 2;
        if ((b & 0x03) == 0x01) c |= NS_EXT;    /* NT flag (Name extension has only small capital) */
        if ((b & 0x0C) == 0x04) c |= NS_BODY;   /* NT flag (Name body has only small capital) */

        sfn[NS] = c;            /* Store NT flag, File name is created */

        return FR_OK;
#endif
}




/*-----------------------------------------------------------------------*/
/* Get file information from directory entry                             */
/*-----------------------------------------------------------------------*/
#if _FS_MINIMIZE <= 1
static
void get_fileinfo (             /* No return code */
        DIR *dj,                        /* Pointer to the directory object */
        FILINFO *fno            /* Pointer to the file information to be filled */
)
{
        UINT i;
        BYTE nt, *dir;
        TCHAR *p, c;


        p = fno->fname;
        if (dj->sect) {
                dir = dj->dir;
                nt = dir[DIR_NTres];            /* NT flag */
                for (i = 0; i < 8; i++) {       /* Copy name body */
                        c = dir[i];
                        if (c == ' ') break;
                        if (c == 0x05) c = (TCHAR)0xE5;
                        if (_USE_LFN && (nt & NS_BODY) && IsUpper(c)) c += 0x20;
#if _LFN_UNICODE
                        if (IsDBCS1(c) && i < 7 && IsDBCS2(dir[i+1]))
                                c = (c << 8) | dir[++i];
                        c = ff_convert(c, 1);
                        if (!c) c = '?';
#endif
                        *p++ = c;
                }
                if (dir[8] != ' ') {            /* Copy name extension */
                        *p++ = '.';
                        for (i = 8; i < 11; i++) {
                                c = dir[i];
                                if (c == ' ') break;
                                if (_USE_LFN && (nt & NS_EXT) && IsUpper(c)) c += 0x20;
#if _LFN_UNICODE
                                if (IsDBCS1(c) && i < 10 && IsDBCS2(dir[i+1]))
                                        c = (c << 8) | dir[++i];
                                c = ff_convert(c, 1);
                                if (!c) c = '?';
#endif
                                *p++ = c;
                        }
                }
                fno->fattrib = dir[DIR_Attr];                           /* Attribute */
                fno->fsize = LD_DWORD(dir+DIR_FileSize);        /* Size */
                fno->fdate = LD_WORD(dir+DIR_WrtDate);          /* Date */
                fno->ftime = LD_WORD(dir+DIR_WrtTime);          /* Time */
        }
        *p = 0;         /* Terminate SFN str by a \0 */

#if _USE_LFN
        if (fno->lfname && fno->lfsize) {
                TCHAR *tp = fno->lfname;
                WCHAR w, *lfn;

                i = 0;
                if (dj->sect && dj->lfn_idx != 0xFFFF) {/* Get LFN if available */
                        lfn = dj->lfn;
                        while ((w = *lfn++) != 0) {                     /* Get an LFN char */
#if !_LFN_UNICODE
                                w = ff_convert(w, 0);                   /* Unicode -> OEM conversion */
                                if (!w) { i = 0; break; }               /* Could not convert, no LFN */
                                if (_DF1S && w >= 0x100)                /* Put 1st byte if it is a DBC (always false on SBCS cfg) */
                                        tp[i++] = (TCHAR)(w >> 8);
#endif
                                if (i >= fno->lfsize - 1) { i = 0; break; }     /* Buffer overflow, no LFN */
                                tp[i++] = (TCHAR)w;
                        }
                }
                tp[i] = 0;      /* Terminate the LFN str by a \0 */
        }
#endif
}
#endif /* _FS_MINIMIZE <= 1 */




/*-----------------------------------------------------------------------*/
/* Follow a file path                                                    */
/*-----------------------------------------------------------------------*/

static
FRESULT follow_path (   /* FR_OK(0): successful, !=0: error code */
        DIR *dj,                        /* Directory object to return last directory and found object */
        const TCHAR *path       /* Full-path string to find a file or directory */
)
{
        FRESULT res;
        BYTE *dir, ns;


#if _FS_RPATH
        if (*path == '/' || *path == '\\') { /* There is a heading separator */
                path++; dj->sclust = 0;         /* Strip it and start from the root dir */
        } else {                                                        /* No heading separator */
                dj->sclust = dj->fs->cdir;      /* Start from the current dir */
        }
#else
        if (*path == '/' || *path == '\\')      /* Strip heading separator if exist */
                path++;
        dj->sclust = 0;                                         /* Start from the root dir */
#endif

        if ((UINT)*path < ' ') {                        /* Nul path means the start directory itself */
                res = dir_sdi(dj, 0);
                dj->dir = 0;

        } else {                                                        /* Follow path */
                for (;;) {
                        res = create_name(dj, &path);   /* Get a segment */
                        if (res != FR_OK) break;
                        res = dir_find(dj);                             /* Find it */
                        ns = *(dj->fn+NS);
                        if (res != FR_OK) {                             /* Failed to find the object */
                                if (res != FR_NO_FILE) break;   /* Abort if any hard error occured */
                                /* Object not found */
                                if (_FS_RPATH && (ns & NS_DOT)) {       /* If dot entry is not exit */
                                        dj->sclust = 0; dj->dir = 0;    /* It is the root dir */
                                        res = FR_OK;
                                        if (!(ns & NS_LAST)) continue;
                                } else {                                                        /* Could not find the object */
                                        if (!(ns & NS_LAST)) res = FR_NO_PATH;
                                }
                                break;
                        }
                        if (ns & NS_LAST) break;                        /* Last segment match. Function completed. */
                        dir = dj->dir;                                          /* There is next segment. Follow the sub directory */
                        if (!(dir[DIR_Attr] & AM_DIR)) {        /* Cannot follow because it is a file */
                                res = FR_NO_PATH; break;
                        }
                        dj->sclust = LD_CLUST(dir);
                }
        }

        return res;
}




/*-----------------------------------------------------------------------*/
/* Load boot record and check if it is an FAT boot record                */
/*-----------------------------------------------------------------------*/

static
BYTE check_fs ( /* 0:The FAT BR, 1:Valid BR but not an FAT, 2:Not a BR, 3:Disk error */
        FATFS *fs,      /* File system object */
        DWORD sect      /* Sector# (lba) to check if it is an FAT boot record or not */
)
{
        if (disk_read(fs->drv, fs->win, sect, 1) != RES_OK)     /* Load boot record */
                return 3;
        if (LD_WORD(&fs->win[BS_55AA]) != 0xAA55)               /* Check record signature (always placed at offset 510 even if the sector size is >512) */
                return 2;

        if ((LD_DWORD(&fs->win[BS_FilSysType]) & 0xFFFFFF) == 0x544146) /* Check "FAT" string */
                return 0;
        if ((LD_DWORD(&fs->win[BS_FilSysType32]) & 0xFFFFFF) == 0x544146)
                return 0;

        return 1;
}




/*-----------------------------------------------------------------------*/
/* Check if the file system object is valid or not                       */
/*-----------------------------------------------------------------------*/

static
FRESULT chk_mounted (   /* FR_OK(0): successful, !=0: any error occurred */
        const TCHAR **path,     /* Pointer to pointer to the path name (drive number) */
        FATFS **rfs,            /* Pointer to pointer to the found file system object */
        BYTE chk_wp                     /* !=0: Check media write protection for write access */
)
{
        BYTE fmt, b, *tbl;
        UINT vol;
        DSTATUS stat;
        DWORD bsect, fasize, tsect, sysect, nclst, szbfat;
        WORD nrsv;
        const TCHAR *p = *path;
        FATFS *fs;

        /* Get logical drive number from the path name */
        vol = p[0] - '0';                                       /* Is there a drive number? */
        if (vol <= 9 && p[1] == ':') {          /* Found a drive number, get and strip it */
                p += 2; *path = p;                              /* Return pointer to the path name */
        } else {                                                        /* No drive number is given */
#if _FS_RPATH
                vol = CurrVol;                                  /* Use current drive */
#else
                vol = 0;                                                /* Use drive 0 */
#endif
        }

        /* Check if the logical drive is valid or not */
        if (vol >= _VOLUMES)                            /* Is the drive number valid? */
                return FR_INVALID_DRIVE;
        *rfs = fs = FatFs[vol];                         /* Return pointer to the corresponding file system object */
        if (!fs) return FR_NOT_ENABLED;         /* Is the file system object available? */

        ENTER_FF(fs);                                           /* Lock file system */

        if (fs->fs_type) {                                      /* If the logical drive has been mounted */
                stat = disk_status(fs->drv);
                if (!(stat & STA_NOINIT)) {             /* and the physical drive is kept initialized (has not been changed), */
#if !_FS_READONLY
                        if (chk_wp && (stat & STA_PROTECT))     /* Check write protection if needed */
                                return FR_WRITE_PROTECTED;
#endif
                        return FR_OK;                           /* The file system object is valid */
                }
        }

        /* The logical drive must be mounted. */
        /* Following code attempts to mount a volume. (analyze BPB and initialize the fs object) */

        fs->fs_type = 0;                                        /* Clear the file system object */
        fs->drv = (BYTE)LD2PD(vol);                     /* Bind the logical drive and a physical drive */
        stat = disk_initialize(fs->drv);        /* Initialize low level disk I/O layer */
        if (stat & STA_NOINIT)                          /* Check if the initialization succeeded */
                return FR_NOT_READY;                    /* Failed to initialize due to no media or hard error */
#if _MAX_SS != 512                                              /* Get disk sector size (variable sector size cfg only) */
        if (disk_ioctl(fs->drv, GET_SECTOR_SIZE, &fs->ssize) != RES_OK)
                return FR_DISK_ERR;
#endif
#if !_FS_READONLY
        if (chk_wp && (stat & STA_PROTECT))     /* Check disk write protection if needed */
                return FR_WRITE_PROTECTED;
#endif
        /* Search FAT partition on the drive. Supports only generic partitionings, FDISK and SFD. */
        fmt = check_fs(fs, bsect = 0);          /* Check sector 0 if it is a VBR */
        if (fmt == 1) {                                         /* Not an FAT-VBR, the disk may be partitioned */
                /* Check the partition listed in top of the partition table */
                tbl = &fs->win[MBR_Table + LD2PT(vol) * 16];    /* Partition table */
                if (tbl[4]) {                                                                   /* Is the partition existing? */
                        bsect = LD_DWORD(&tbl[8]);                                      /* Partition offset in LBA */
                        fmt = check_fs(fs, bsect);                                      /* Check the partition */
                }
        }
        if (fmt == 3) return FR_DISK_ERR;
        if (fmt) return FR_NO_FILESYSTEM;                                       /* No FAT volume is found */

        /* Following code initializes the file system object */

        if (LD_WORD(fs->win+BPB_BytsPerSec) != SS(fs))          /* (BPB_BytsPerSec must be equal to the physical sector size) */
                return FR_NO_FILESYSTEM;

        fasize = LD_WORD(fs->win+BPB_FATSz16);                          /* Number of sectors per FAT */
        if (!fasize) fasize = LD_DWORD(fs->win+BPB_FATSz32);
        fs->fsize = fasize;

        fs->n_fats = b = fs->win[BPB_NumFATs];                          /* Number of FAT copies */
        if (b != 1 && b != 2) return FR_NO_FILESYSTEM;          /* (Must be 1 or 2) */
        fasize *= b;                                                                            /* Number of sectors for FAT area */

        fs->csize = b = fs->win[BPB_SecPerClus];                        /* Number of sectors per cluster */
        if (!b || (b & (b - 1))) return FR_NO_FILESYSTEM;       /* (Must be power of 2) */

        fs->n_rootdir = LD_WORD(fs->win+BPB_RootEntCnt);        /* Number of root directory entries */
        if (fs->n_rootdir % (SS(fs) / 32)) return FR_NO_FILESYSTEM;     /* (BPB_RootEntCnt must be sector aligned) */

        tsect = LD_WORD(fs->win+BPB_TotSec16);                          /* Number of sectors on the volume */
        if (!tsect) tsect = LD_DWORD(fs->win+BPB_TotSec32);

        nrsv = LD_WORD(fs->win+BPB_RsvdSecCnt);                         /* Number of reserved sectors */
        if (!nrsv) return FR_NO_FILESYSTEM;                                     /* (BPB_RsvdSecCnt must not be 0) */

        /* Determine the FAT sub type */
        sysect = nrsv + fasize + fs->n_rootdir / (SS(fs) / 32); /* RSV+FAT+DIR */
        if (tsect < sysect) return FR_NO_FILESYSTEM;            /* (Invalid volume size) */
        nclst = (tsect - sysect) / fs->csize;                           /* Number of clusters */
        if (!nclst) return FR_NO_FILESYSTEM;                            /* (Invalid volume size) */
        fmt = FS_FAT12;
        if (nclst >= MIN_FAT16) fmt = FS_FAT16;
        if (nclst >= MIN_FAT32) fmt = FS_FAT32;

        /* Boundaries and Limits */
        fs->n_fatent = nclst + 2;                                                       /* Number of FAT entries */
        fs->database = bsect + sysect;                                          /* Data start sector */
        fs->fatbase = bsect + nrsv;                                             /* FAT start sector */
        if (fmt == FS_FAT32) {
                if (fs->n_rootdir) return FR_NO_FILESYSTEM;             /* (BPB_RootEntCnt must be 0) */
                fs->dirbase = LD_DWORD(fs->win+BPB_RootClus);   /* Root directory start cluster */
                szbfat = fs->n_fatent * 4;                                              /* (Required FAT size) */
        } else {
                if (!fs->n_rootdir)     return FR_NO_FILESYSTEM;        /* (BPB_RootEntCnt must not be 0) */
                fs->dirbase = fs->fatbase + fasize;                             /* Root directory start sector */
                szbfat = (fmt == FS_FAT16) ?                                    /* (Required FAT size) */
                        fs->n_fatent * 2 : fs->n_fatent * 3 / 2 + (fs->n_fatent & 1);
        }
        if (fs->fsize < (szbfat + (SS(fs) - 1)) / SS(fs))       /* (FAT size must not be less than FAT sectors */
                return FR_NO_FILESYSTEM;

#if !_FS_READONLY
        /* Initialize cluster allocation information */
        fs->free_clust = 0xFFFFFFFF;
        fs->last_clust = 0;

        /* Get fsinfo if available */
        if (fmt == FS_FAT32) {
                fs->fsi_flag = 0;
                fs->fsi_sector = bsect + LD_WORD(fs->win+BPB_FSInfo);
                if (disk_read(fs->drv, fs->win, fs->fsi_sector, 1) == RES_OK &&
                        LD_WORD(fs->win+BS_55AA) == 0xAA55 &&
                        LD_DWORD(fs->win+FSI_LeadSig) == 0x41615252 &&
                        LD_DWORD(fs->win+FSI_StrucSig) == 0x61417272) {
                                fs->last_clust = LD_DWORD(fs->win+FSI_Nxt_Free);
                                fs->free_clust = LD_DWORD(fs->win+FSI_Free_Count);
                }
        }
#endif
        fs->fs_type = fmt;              /* FAT sub-type */
        fs->id = ++Fsid;                /* File system mount ID */
        fs->winsect = 0;                /* Invalidate sector cache */
        fs->wflag = 0;
#if _FS_RPATH
        fs->cdir = 0;                   /* Current directory (root dir) */
#endif
#if _FS_SHARE                           /* Clear file lock semaphores */
        clear_lock(fs);
#endif

        return FR_OK;
}




/*-----------------------------------------------------------------------*/
/* Check if the file/dir object is valid or not                          */
/*-----------------------------------------------------------------------*/

static
FRESULT validate (      /* FR_OK(0): The object is valid, !=0: Invalid */
        FATFS *fs,              /* Pointer to the file system object */
        WORD id                 /* Member id of the target object to be checked */
)
{
        if (!fs || !fs->fs_type || fs->id != id)
                return FR_INVALID_OBJECT;

        ENTER_FF(fs);           /* Lock file system */

        if (disk_status(fs->drv) & STA_NOINIT)
                return FR_NOT_READY;

        return FR_OK;
}




/*--------------------------------------------------------------------------

   Public Functions

--------------------------------------------------------------------------*/



/*-----------------------------------------------------------------------*/
/* Mount/Unmount a Logical Drive                                         */
/*-----------------------------------------------------------------------*/

FRESULT f_mount (
        BYTE vol,               /* Logical drive number to be mounted/unmounted */
        FATFS *fs               /* Pointer to new file system object (NULL for unmount)*/
)
{
        FATFS *rfs;


        if (vol >= _VOLUMES)                    /* Check if the drive number is valid */
                return FR_INVALID_DRIVE;
        rfs = FatFs[vol];                               /* Get current fs object */

        if (rfs) {
#if _FS_SHARE
                clear_lock(rfs);
#endif
#if _FS_REENTRANT                                       /* Discard sync object of the current volume */
                if (!ff_del_syncobj(rfs->sobj)) return FR_INT_ERR;
#endif
                rfs->fs_type = 0;                       /* Clear old fs object */
        }

        if (fs) {
                fs->fs_type = 0;                        /* Clear new fs object */
#if _FS_REENTRANT                                       /* Create sync object for the new volume */
                if (!ff_cre_syncobj(vol, &fs->sobj)) return FR_INT_ERR;
#endif
        }
        FatFs[vol] = fs;                                /* Register new fs object */

        return FR_OK;
}




/*-----------------------------------------------------------------------*/
/* Open or Create a File                                                 */
/*-----------------------------------------------------------------------*/

FRESULT f_open (
        FIL *fp,                        /* Pointer to the blank file object */
        const TCHAR *path,      /* Pointer to the file name */
        BYTE mode                       /* Access mode and file open mode flags */
)
{
        FRESULT res;
        DIR dj;
        BYTE *dir;
        DEF_NAMEBUF;


        fp->fs = 0;                     /* Clear file object */

#if !_FS_READONLY
        mode &= FA_READ | FA_WRITE | FA_CREATE_ALWAYS | FA_OPEN_ALWAYS | FA_CREATE_NEW;
        res = chk_mounted(&path, &dj.fs, (BYTE)(mode & ~FA_READ));
#else
        mode &= FA_READ;
        res = chk_mounted(&path, &dj.fs, 0);
#endif
        INIT_BUF(dj);
        if (res == FR_OK)
                res = follow_path(&dj, path);   /* Follow the file path */
        dir = dj.dir;

#if !_FS_READONLY       /* R/W configuration */
        if (res == FR_OK) {
                if (!dir)       /* Current dir itself */
                        res = FR_INVALID_NAME;
#if _FS_SHARE
                else
                        res = chk_lock(&dj, (mode & ~FA_READ) ? 1 : 0);
#endif
        }
        /* Create or Open a file */
        if (mode & (FA_CREATE_ALWAYS | FA_OPEN_ALWAYS | FA_CREATE_NEW)) {
                DWORD dw, cl;

                if (res != FR_OK) {                                     /* No file, create new */
                        if (res == FR_NO_FILE)                  /* There is no file to open, create a new entry */
#if _FS_SHARE
                                res = enq_lock(dj.fs) ? dir_register(&dj) : FR_TOO_MANY_OPEN_FILES;
#else
                                res = dir_register(&dj);
#endif
                        mode |= FA_CREATE_ALWAYS;               /* File is created */
                        dir = dj.dir;                                   /* New entry */
                }
                else {                                                          /* Any object is already existing */
                        if (mode & FA_CREATE_NEW) {             /* Cannot create new */
                                res = FR_EXIST;
                        } else {
                                if (dir[DIR_Attr] & (AM_RDO | AM_DIR))  /* Cannot overwrite it (R/O or DIR) */
                                        res = FR_DENIED;
                        }
                }
                if (res == FR_OK && (mode & FA_CREATE_ALWAYS)) {        /* Truncate it if overwrite mode */
                        dw = get_fattime();                                     /* Created time */
                        ST_DWORD(dir+DIR_CrtTime, dw);
                        dir[DIR_Attr] = 0;                                      /* Reset attribute */
                        ST_DWORD(dir+DIR_FileSize, 0);          /* size = 0 */
                        cl = LD_CLUST(dir);                                     /* Get start cluster */
                        ST_CLUST(dir, 0);                                       /* cluster = 0 */
                        dj.fs->wflag = 1;
                        if (cl) {                                                       /* Remove the cluster chain if exist */
                                dw = dj.fs->winsect;
                                res = remove_chain(dj.fs, cl);
                                if (res == FR_OK) {
                                        dj.fs->last_clust = cl - 1;     /* Reuse the cluster hole */
                                        res = move_window(dj.fs, dw);
                                }
                        }
                }
        }
        else {  /* Open an existing file */
                if (res == FR_OK) {                                             /* Follow succeeded */
                        if (dir[DIR_Attr] & AM_DIR) {           /* It is a directory */
                                res = FR_NO_FILE;
                        } else {
                                if ((mode & FA_WRITE) && (dir[DIR_Attr] & AM_RDO)) /* R/O violation */
                                        res = FR_DENIED;
                        }
                }
        }
        if (res == FR_OK) {
                if (mode & FA_CREATE_ALWAYS)                    /* Set file change flag if created or overwritten */
                        mode |= FA__WRITTEN;
                fp->dir_sect = dj.fs->winsect;                  /* Pointer to the directory entry */
                fp->dir_ptr = dir;
#if _FS_SHARE
                fp->lockid = inc_lock(&dj, (mode & ~FA_READ) ? 1 : 0);
                if (!fp->lockid) res = FR_INT_ERR;
#endif
        }

#else                           /* R/O configuration */
        if (res == FR_OK) {                                     /* Follow succeeded */
                if (!dir) {                                             /* Current dir itself */
                        res = FR_INVALID_NAME;
                } else {
                        if (dir[DIR_Attr] & AM_DIR)     /* It is a directory */
                                res = FR_NO_FILE;
                }
        }
#endif
        FREE_BUF();

        if (res == FR_OK) {
                fp->flag = mode;                                        /* File access mode */
                fp->org_clust = LD_CLUST(dir);          /* File start cluster */
                fp->fsize = LD_DWORD(dir+DIR_FileSize); /* File size */
                fp->fptr = 0;                                           /* File pointer */
                fp->dsect = 0;
#if _USE_FASTSEEK
                fp->cltbl = 0;                                          /* No cluster link map table */
#endif
                fp->fs = dj.fs; fp->id = dj.fs->id;     /* Validate file object */
        }

        LEAVE_FF(dj.fs, res);
}




/*-----------------------------------------------------------------------*/
/* Read File                                                             */
/*-----------------------------------------------------------------------*/

FRESULT f_read (
        FIL *fp,                /* Pointer to the file object */
        void *buff,             /* Pointer to data buffer */
        UINT btr,               /* Number of bytes to read */
        UINT *br                /* Pointer to number of bytes read */
)
{
        FRESULT res;
        DWORD clst, sect, remain;
        UINT rcnt, cc;
        BYTE csect, *rbuff = buff;


        *br = 0;        /* Initialize byte counter */

        res = validate(fp->fs, fp->id);                                 /* Check validity of the object */
        if (res != FR_OK) LEAVE_FF(fp->fs, res);
        if (fp->flag & FA__ERROR)                                               /* Check abort flag */
                LEAVE_FF(fp->fs, FR_INT_ERR);
        if (!(fp->flag & FA_READ))                                              /* Check access mode */
                LEAVE_FF(fp->fs, FR_DENIED);
        remain = fp->fsize - fp->fptr;
        if (btr > remain) btr = (UINT)remain;                   /* Truncate btr by remaining bytes */

        for ( ;  btr;                                                                   /* Repeat until all data transferred */
                rbuff += rcnt, fp->fptr += rcnt, *br += rcnt, btr -= rcnt) {
                if ((fp->fptr % SS(fp->fs)) == 0) {                     /* On the sector boundary? */
                        csect = (BYTE)(fp->fptr / SS(fp->fs) & (fp->fs->csize - 1));    /* Sector offset in the cluster */
                        if (!csect) {                                                   /* On the cluster boundary? */
                                clst = (fp->fptr == 0) ?                        /* On the top of the file? */
                                        fp->org_clust : get_fat(fp->fs, fp->curr_clust);
                                if (clst <= 1) ABORT(fp->fs, FR_INT_ERR);
                                if (clst == 0xFFFFFFFF) ABORT(fp->fs, FR_DISK_ERR);
                                fp->curr_clust = clst;                          /* Update current cluster */
                        }
                        sect = clust2sect(fp->fs, fp->curr_clust);      /* Get current sector */
                        if (!sect) ABORT(fp->fs, FR_INT_ERR);
                        sect += csect;
                        cc = btr / SS(fp->fs);                                  /* When remaining bytes >= sector size, */
                        if (cc) {                                                               /* Read maximum contiguous sectors directly */
                                if (csect + cc > fp->fs->csize)         /* Clip at cluster boundary */
                                        cc = fp->fs->csize - csect;
                                if (disk_read(fp->fs->drv, rbuff, sect, (BYTE)cc) != RES_OK)
                                        ABORT(fp->fs, FR_DISK_ERR);
#if !_FS_READONLY && _FS_MINIMIZE <= 2                          /* Replace one of the read sectors with cached data if it contains a dirty sector */
#if _FS_TINY
                                if (fp->fs->wflag && fp->fs->winsect - sect < cc)
                                        mem_cpy(rbuff + ((fp->fs->winsect - sect) * SS(fp->fs)), fp->fs->win, SS(fp->fs));
#else
                                if ((fp->flag & FA__DIRTY) && fp->dsect - sect < cc)
                                        mem_cpy(rbuff + ((fp->dsect - sect) * SS(fp->fs)), fp->buf, SS(fp->fs));
#endif
#endif
                                rcnt = SS(fp->fs) * cc;                         /* Number of bytes transferred */
                                continue;
                        }
#if !_FS_TINY
#if !_FS_READONLY
                        if (fp->flag & FA__DIRTY) {                             /* Write sector I/O buffer if needed */
                                if (disk_write(fp->fs->drv, fp->buf, fp->dsect, 1) != RES_OK)
                                        ABORT(fp->fs, FR_DISK_ERR);
                                fp->flag &= ~FA__DIRTY;
                        }
#endif
                        if (fp->dsect != sect) {                                /* Fill sector buffer with file data */
                                if (disk_read(fp->fs->drv, fp->buf, sect, 1) != RES_OK)
                                        ABORT(fp->fs, FR_DISK_ERR);
                        }
#endif
                        fp->dsect = sect;
                }
                rcnt = SS(fp->fs) - (fp->fptr % SS(fp->fs));    /* Get partial sector data from sector buffer */
                if (rcnt > btr) rcnt = btr;
#if _FS_TINY
                if (move_window(fp->fs, fp->dsect))                     /* Move sector window */
                        ABORT(fp->fs, FR_DISK_ERR);
                mem_cpy(rbuff, &fp->fs->win[fp->fptr % SS(fp->fs)], rcnt);      /* Pick partial sector */
#else
                mem_cpy(rbuff, &fp->buf[fp->fptr % SS(fp->fs)], rcnt);  /* Pick partial sector */
#endif
        }

        LEAVE_FF(fp->fs, FR_OK);
}




#if !_FS_READONLY
/*-----------------------------------------------------------------------*/
/* Write File                                                            */
/*-----------------------------------------------------------------------*/

FRESULT f_write (
        FIL *fp,                        /* Pointer to the file object */
        const void *buff,       /* Pointer to the data to be written */
        UINT btw,                       /* Number of bytes to write */
        UINT *bw                        /* Pointer to number of bytes written */
)
{
        FRESULT res;
        DWORD clst, sect;
        UINT wcnt, cc;
        const BYTE *wbuff = buff;
        BYTE csect;


        *bw = 0;        /* Initialize byte counter */

        res = validate(fp->fs, fp->id);                                 /* Check validity of the object */
        if (res != FR_OK) LEAVE_FF(fp->fs, res);
        if (fp->flag & FA__ERROR)                                               /* Check abort flag */
                LEAVE_FF(fp->fs, FR_INT_ERR);
        if (!(fp->flag & FA_WRITE))                                             /* Check access mode */
                LEAVE_FF(fp->fs, FR_DENIED);
        if (fp->fsize + btw < fp->fsize) btw = 0;               /* File size cannot reach 4GB */

        for ( ;  btw;                                                                   /* Repeat until all data transferred */
                wbuff += wcnt, fp->fptr += wcnt, *bw += wcnt, btw -= wcnt) {
                if ((fp->fptr % SS(fp->fs)) == 0) {                     /* On the sector boundary? */
                        csect = (BYTE)(fp->fptr / SS(fp->fs) & (fp->fs->csize - 1));    /* Sector offset in the cluster */
                        if (!csect) {                                                   /* On the cluster boundary? */
                                if (fp->fptr == 0) {                            /* On the top of the file? */
                                        clst = fp->org_clust;                   /* Follow from the origin */
                                        if (clst == 0)                                  /* When there is no cluster chain, */
                                                fp->org_clust = clst = create_chain(fp->fs, 0); /* Create a new cluster chain */
                                } else {                                                        /* Middle or end of the file */
                                        clst = create_chain(fp->fs, fp->curr_clust);                    /* Follow or stretch cluster chain */
                                }
                                if (clst == 0) break;                           /* Could not allocate a new cluster (disk full) */
                                if (clst == 1) ABORT(fp->fs, FR_INT_ERR);
                                if (clst == 0xFFFFFFFF) ABORT(fp->fs, FR_DISK_ERR);
                                fp->curr_clust = clst;                          /* Update current cluster */
                        }
#if _FS_TINY
                        if (fp->fs->winsect == fp->dsect && move_window(fp->fs, 0))     /* Write back data buffer prior to following direct transfer */
                                ABORT(fp->fs, FR_DISK_ERR);
#else
                        if (fp->flag & FA__DIRTY) {             /* Write back data buffer prior to following direct transfer */
                                if (disk_write(fp->fs->drv, fp->buf, fp->dsect, 1) != RES_OK)
                                        ABORT(fp->fs, FR_DISK_ERR);
                                fp->flag &= ~FA__DIRTY;
                        }
#endif
                        sect = clust2sect(fp->fs, fp->curr_clust);      /* Get current sector */
                        if (!sect) ABORT(fp->fs, FR_INT_ERR);
                        sect += csect;
                        cc = btw / SS(fp->fs);                                  /* When remaining bytes >= sector size, */
                        if (cc) {                                                               /* Write maximum contiguous sectors directly */
                                if (csect + cc > fp->fs->csize)         /* Clip at cluster boundary */
                                        cc = fp->fs->csize - csect;
                                if (disk_write(fp->fs->drv, wbuff, sect, (BYTE)cc) != RES_OK)
                                        ABORT(fp->fs, FR_DISK_ERR);
#if _FS_TINY
                                if (fp->fs->winsect - sect < cc) {      /* Refill sector cache if it gets dirty by the direct write */
                                        mem_cpy(fp->fs->win, wbuff + ((fp->fs->winsect - sect) * SS(fp->fs)), SS(fp->fs));
                                        fp->fs->wflag = 0;
                                }
#else
                                if (fp->dsect - sect < cc) {            /* Refill sector cache if it gets dirty by the direct write */
                                        mem_cpy(fp->buf, wbuff + ((fp->dsect - sect) * SS(fp->fs)), SS(fp->fs));
                                        fp->flag &= ~FA__DIRTY;
                                }
#endif
                                wcnt = SS(fp->fs) * cc;                         /* Number of bytes transferred */
                                continue;
                        }
#if _FS_TINY
                        if (fp->fptr >= fp->fsize) {                    /* Avoid silly buffer filling at growing edge */
                                if (move_window(fp->fs, 0)) ABORT(fp->fs, FR_DISK_ERR);
                                fp->fs->winsect = sect;
                        }
#else
                        if (fp->dsect != sect) {                                /* Fill sector buffer with file data */
                                if (fp->fptr < fp->fsize &&
                                        disk_read(fp->fs->drv, fp->buf, sect, 1) != RES_OK)
                                                ABORT(fp->fs, FR_DISK_ERR);
                        }
#endif
                        fp->dsect = sect;
                }
                wcnt = SS(fp->fs) - (fp->fptr % SS(fp->fs));/* Put partial sector into file I/O buffer */
                if (wcnt > btw) wcnt = btw;
#if _FS_TINY
                if (move_window(fp->fs, fp->dsect))                     /* Move sector window */
                        ABORT(fp->fs, FR_DISK_ERR);
                mem_cpy(&fp->fs->win[fp->fptr % SS(fp->fs)], wbuff, wcnt);      /* Fit partial sector */
                fp->fs->wflag = 1;
#else
                mem_cpy(&fp->buf[fp->fptr % SS(fp->fs)], wbuff, wcnt);  /* Fit partial sector */
                fp->flag |= FA__DIRTY;
#endif
        }

        if (fp->fptr > fp->fsize) fp->fsize = fp->fptr; /* Update file size if needed */
        fp->flag |= FA__WRITTEN;                                                /* Set file change flag */

        LEAVE_FF(fp->fs, FR_OK);
}




/*-----------------------------------------------------------------------*/
/* Synchronize the File Object                                           */
/*-----------------------------------------------------------------------*/

FRESULT f_sync (
        FIL *fp         /* Pointer to the file object */
)
{
        FRESULT res;
        DWORD tim;
        BYTE *dir;


        res = validate(fp->fs, fp->id);         /* Check validity of the object */
        if (res == FR_OK) {
                if (fp->flag & FA__WRITTEN) {   /* Has the file been written? */
#if !_FS_TINY   /* Write-back dirty buffer */
                        if (fp->flag & FA__DIRTY) {
                                if (disk_write(fp->fs->drv, fp->buf, fp->dsect, 1) != RES_OK)
                                        LEAVE_FF(fp->fs, FR_DISK_ERR);
                                fp->flag &= ~FA__DIRTY;
                        }
#endif
                        /* Update the directory entry */
                        res = move_window(fp->fs, fp->dir_sect);
                        if (res == FR_OK) {
                                dir = fp->dir_ptr;
                                dir[DIR_Attr] |= AM_ARC;                                        /* Set archive bit */
                                ST_DWORD(dir+DIR_FileSize, fp->fsize);          /* Update file size */
                                ST_CLUST(dir, fp->org_clust);                           /* Update start cluster */
                                tim = get_fattime();                                            /* Update updated time */
                                ST_DWORD(dir+DIR_WrtTime, tim);
                                fp->flag &= ~FA__WRITTEN;
                                fp->fs->wflag = 1;
                                res = sync(fp->fs);
                        }
                }
        }

        LEAVE_FF(fp->fs, res);
}

#endif /* !_FS_READONLY */




/*-----------------------------------------------------------------------*/
/* Close File                                                            */
/*-----------------------------------------------------------------------*/

FRESULT f_close (
        FIL *fp         /* Pointer to the file object to be closed */
)
{
        FRESULT res;

#if _FS_READONLY
        FATFS *fs = fp->fs;
        res = validate(fs, fp->id);
        if (res == FR_OK) fp->fs = 0;   /* Discard file object */
        LEAVE_FF(fs, res);

#else
        res = f_sync(fp);               /* Flush cached data */
#if _FS_SHARE
        if (res == FR_OK) {             /* Decrement open counter */
#if _FS_REENTRANT
                res = validate(fp->fs, fp->id);
                if (res == FR_OK) {
                        res = dec_lock(fp->lockid);     
                        unlock_fs(fp->fs, FR_OK);
                }
#else
                res = dec_lock(fp->lockid);
#endif
        }
#endif
        if (res == FR_OK) fp->fs = 0;   /* Discard file object */
        return res;
#endif
}




/*-----------------------------------------------------------------------*/
/* Current Drive/Directory Handlings                                     */
/*-----------------------------------------------------------------------*/

#if _FS_RPATH >= 1

FRESULT f_chdrive (
        BYTE drv                /* Drive number */
)
{
        if (drv >= _VOLUMES) return FR_INVALID_DRIVE;

        CurrVol = drv;

        return FR_OK;
}



FRESULT f_chdir (
        const TCHAR *path       /* Pointer to the directory path */
)
{
        FRESULT res;
        DIR dj;
        DEF_NAMEBUF;


        res = chk_mounted(&path, &dj.fs, 0);
        if (res == FR_OK) {
                INIT_BUF(dj);
                res = follow_path(&dj, path);           /* Follow the path */
                FREE_BUF();
                if (res == FR_OK) {                                     /* Follow completed */
                        if (!dj.dir) {
                                dj.fs->cdir = dj.sclust;        /* Start directory itself */
                        } else {
                                if (dj.dir[DIR_Attr] & AM_DIR)  /* Reached to the directory */
                                        dj.fs->cdir = LD_CLUST(dj.dir);
                                else
                                        res = FR_NO_PATH;               /* Reached but a file */
                        }
                }
                if (res == FR_NO_FILE) res = FR_NO_PATH;
        }

        LEAVE_FF(dj.fs, res);
}


#if _FS_RPATH >= 2
FRESULT f_getcwd (
        TCHAR *path,    /* Pointer to the directory path */
        UINT sz_path    /* Size of path */
)
{
        FRESULT res;
        DIR dj;
        UINT i, n;
        DWORD ccl;
        TCHAR *tp;
        FILINFO fno;
        DEF_NAMEBUF;


        *path = 0;
        res = chk_mounted((const TCHAR**)&path, &dj.fs, 0);     /* Get current volume */
        if (res == FR_OK) {
                INIT_BUF(dj);
                i = sz_path;            /* Bottom of buffer (dir stack base) */
                dj.sclust = dj.fs->cdir;                        /* Start to follow upper dir from current dir */
                while ((ccl = dj.sclust) != 0) {        /* Repeat while current dir is a sub-dir */
                        res = dir_sdi(&dj, 1);                  /* Get parent dir */
                        if (res != FR_OK) break;
                        res = dir_read(&dj);
                        if (res != FR_OK) break;
                        dj.sclust = LD_CLUST(dj.dir);   /* Goto parent dir */
                        res = dir_sdi(&dj, 0);
                        if (res != FR_OK) break;
                        do {                                                    /* Find the entry links to the child dir */
                                res = dir_read(&dj);
                                if (res != FR_OK) break;
                                if (ccl == LD_CLUST(dj.dir)) break;     /* Found the entry */
                                res = dir_next(&dj, 0); 
                        } while (res == FR_OK);
                        if (res == FR_NO_FILE) res = FR_INT_ERR;/* It cannot be 'not found'. */
                        if (res != FR_OK) break;
#if _USE_LFN
                        fno.lfname = path;
                        fno.lfsize = i;
#endif
                        get_fileinfo(&dj, &fno);                /* Get the dir name and push it to the buffer */
                        tp = fno.fname;
                        if (_USE_LFN && *path) tp = path;
                        for (n = 0; tp[n]; n++) ;
                        if (i < n + 3) {
                                res = FR_NOT_ENOUGH_CORE; break;
                        }
                        while (n) path[--i] = tp[--n];
                        path[--i] = '/';
                }
                tp = path;
                if (res == FR_OK) {
                        *tp++ = '0' + CurrVol;                  /* Put drive number */
                        *tp++ = ':';
                        if (i == sz_path) {                             /* Root-dir */
                                *tp++ = '/';
                        } else {                                                /* Sub-dir */
                                do              /* Add stacked path str */
                                        *tp++ = path[i++];
                                while (i < sz_path);
                        }
                }
                *tp = 0;
                FREE_BUF();
        }

        LEAVE_FF(dj.fs, res);
}
#endif /* _FS_RPATH >= 2 */
#endif /* _FS_RPATH >= 1 */



#if _FS_MINIMIZE <= 2
/*-----------------------------------------------------------------------*/
/* Seek File R/W Pointer                                                 */
/*-----------------------------------------------------------------------*/

FRESULT f_lseek (
        FIL *fp,                /* Pointer to the file object */
        DWORD ofs               /* File pointer from top of file */
)
{
        FRESULT res;


        res = validate(fp->fs, fp->id);         /* Check validity of the object */
        if (res != FR_OK) LEAVE_FF(fp->fs, res);
        if (fp->flag & FA__ERROR)                       /* Check abort flag */
                LEAVE_FF(fp->fs, FR_INT_ERR);

#if _USE_FASTSEEK
        if (fp->cltbl) {        /* Fast seek */
                DWORD cl, pcl, ncl, tcl, dsc, tlen, *tbl = fp->cltbl;
                BYTE csc;

                tlen = *tbl++;
                if (ofs == CREATE_LINKMAP) {    /* Create link map table */
                        cl = fp->org_clust;
                        if (cl) {
                                do {
                                        if (tlen < 4) { /* Not enough table items */
                                                res = FR_NOT_ENOUGH_CORE; break;
                                        }
                                        tcl = cl; ncl = 0;
                                        do {            /* Get a fragment and store the top and length */
                                                pcl = cl; ncl++;
                                                cl = get_fat(fp->fs, cl);
                                                if (cl <= 1) ABORT(fp->fs, FR_INT_ERR);
                                                if (cl == 0xFFFFFFFF) ABORT(fp->fs, FR_DISK_ERR);
                                        } while (cl == pcl + 1);
                                        *tbl++ = ncl; *tbl++ = tcl;
                                        tlen -= 2;
                                } while (cl < fp->fs->n_fatent);
                        }
                        *tbl = 0;       /* Terminate table */

                } else {                                                /* Fast seek */
                        if (ofs > fp->fsize)            /* Clip offset at the file size */
                                ofs = fp->fsize;
                        fp->fptr = ofs;                         /* Set file pointer */
                        if (ofs) {
                                dsc = (ofs - 1) / SS(fp->fs);
                                cl = dsc / fp->fs->csize;
                                for (;;) {
                                        ncl = *tbl++;
                                        if (!ncl) ABORT(fp->fs, FR_INT_ERR);
                                        if (cl < ncl) break;
                                        cl -= ncl; tbl++;
                                }
                                fp->curr_clust = cl + *tbl;
                                csc = (BYTE)(dsc & (fp->fs->csize - 1));
                                dsc = clust2sect(fp->fs, fp->curr_clust);
                                if (!dsc) ABORT(fp->fs, FR_INT_ERR);
                                dsc += csc;
                                if (fp->fptr % SS(fp->fs) && dsc != fp->dsect) {
#if !_FS_TINY
#if !_FS_READONLY
                                        if (fp->flag & FA__DIRTY) {             /* Flush dirty buffer if needed */
                                                if (disk_write(fp->fs->drv, fp->buf, fp->dsect, 1) != RES_OK)
                                                        ABORT(fp->fs, FR_DISK_ERR);
                                                fp->flag &= ~FA__DIRTY;
                                        }
#endif
                                        if (disk_read(fp->fs->drv, fp->buf, dsc, 1) != RES_OK)
                                                ABORT(fp->fs, FR_DISK_ERR);
#endif
                                        fp->dsect = dsc;
                                }
                        }
                }
        } else
#endif

        /* Normal Seek */
        {
                DWORD clst, bcs, nsect, ifptr;

                if (ofs > fp->fsize                                     /* In read-only mode, clip offset with the file size */
#if !_FS_READONLY
                         && !(fp->flag & FA_WRITE)
#endif
                        ) ofs = fp->fsize;

                ifptr = fp->fptr;
                fp->fptr = nsect = 0;
                if (ofs) {
                        bcs = (DWORD)fp->fs->csize * SS(fp->fs);        /* Cluster size (byte) */
                        if (ifptr > 0 &&
                                (ofs - 1) / bcs >= (ifptr - 1) / bcs) { /* When seek to same or following cluster, */
                                fp->fptr = (ifptr - 1) & ~(bcs - 1);    /* start from the current cluster */
                                ofs -= fp->fptr;
                                clst = fp->curr_clust;
                        } else {                                                                        /* When seek to back cluster, */
                                clst = fp->org_clust;                                   /* start from the first cluster */
#if !_FS_READONLY
                                if (clst == 0) {                                                /* If no cluster chain, create a new chain */
                                        clst = create_chain(fp->fs, 0);
                                        if (clst == 1) ABORT(fp->fs, FR_INT_ERR);
                                        if (clst == 0xFFFFFFFF) ABORT(fp->fs, FR_DISK_ERR);
                                        fp->org_clust = clst;
                                }
#endif
                                fp->curr_clust = clst;
                        }
                        if (clst != 0) {
                                while (ofs > bcs) {                                             /* Cluster following loop */
#if !_FS_READONLY
                                        if (fp->flag & FA_WRITE) {                      /* Check if in write mode or not */
                                                clst = create_chain(fp->fs, clst);      /* Force stretch if in write mode */
                                                if (clst == 0) {                                /* When disk gets full, clip file size */
                                                        ofs = bcs; break;
                                                }
                                        } else
#endif
                                                clst = get_fat(fp->fs, clst);   /* Follow cluster chain if not in write mode */
                                        if (clst == 0xFFFFFFFF) ABORT(fp->fs, FR_DISK_ERR);
                                        if (clst <= 1 || clst >= fp->fs->n_fatent) ABORT(fp->fs, FR_INT_ERR);
                                        fp->curr_clust = clst;
                                        fp->fptr += bcs;
                                        ofs -= bcs;
                                }
                                fp->fptr += ofs;
                                if (ofs % SS(fp->fs)) {
                                        nsect = clust2sect(fp->fs, clst);       /* Current sector */
                                        if (!nsect) ABORT(fp->fs, FR_INT_ERR);
                                        nsect += ofs / SS(fp->fs);
                                }
                        }
                }
                if (fp->fptr % SS(fp->fs) && nsect != fp->dsect) {
#if !_FS_TINY
#if !_FS_READONLY
                        if (fp->flag & FA__DIRTY) {                     /* Flush dirty buffer if needed */
                                if (disk_write(fp->fs->drv, fp->buf, fp->dsect, 1) != RES_OK)
                                        ABORT(fp->fs, FR_DISK_ERR);
                                fp->flag &= ~FA__DIRTY;
                        }
#endif
                        if (disk_read(fp->fs->drv, fp->buf, nsect, 1) != RES_OK)
                                ABORT(fp->fs, FR_DISK_ERR);
#endif
                        fp->dsect = nsect;
                }
#if !_FS_READONLY
                if (fp->fptr > fp->fsize) {                     /* Set change flag if the file size is extended */
                        fp->fsize = fp->fptr;
                        fp->flag |= FA__WRITTEN;
                }
#endif
        }

        LEAVE_FF(fp->fs, res);
}



#if _FS_MINIMIZE <= 1
/*-----------------------------------------------------------------------*/
/* Create a Directroy Object                                             */
/*-----------------------------------------------------------------------*/

FRESULT f_opendir (
        DIR *dj,                        /* Pointer to directory object to create */
        const TCHAR *path       /* Pointer to the directory path */
)
{
        FRESULT res;
        DEF_NAMEBUF;


        res = chk_mounted(&path, &dj->fs, 0);
        if (res == FR_OK) {
                INIT_BUF(*dj);
                res = follow_path(dj, path);                    /* Follow the path to the directory */
                FREE_BUF();
                if (res == FR_OK) {                                             /* Follow completed */
                        if (dj->dir) {                                          /* It is not the root dir */
                                if (dj->dir[DIR_Attr] & AM_DIR) {       /* The object is a directory */
                                        dj->sclust = LD_CLUST(dj->dir);
                                } else {                                                /* The object is not a directory */
                                        res = FR_NO_PATH;
                                }
                        }
                        if (res == FR_OK) {
                                dj->id = dj->fs->id;
                                res = dir_sdi(dj, 0);                   /* Rewind dir */
                        }
                }
                if (res == FR_NO_FILE) res = FR_NO_PATH;
        }

        LEAVE_FF(dj->fs, res);
}




/*-----------------------------------------------------------------------*/
/* Read Directory Entry in Sequense                                      */
/*-----------------------------------------------------------------------*/

FRESULT f_readdir (
        DIR *dj,                        /* Pointer to the open directory object */
        FILINFO *fno            /* Pointer to file information to return */
)
{
        FRESULT res;
        DEF_NAMEBUF;


        res = validate(dj->fs, dj->id);                 /* Check validity of the object */
        if (res == FR_OK) {
                if (!fno) {
                        res = dir_sdi(dj, 0);                   /* Rewind the directory object */
                } else {
                        INIT_BUF(*dj);
                        res = dir_read(dj);                             /* Read an directory item */
                        if (res == FR_NO_FILE) {                /* Reached end of dir */
                                dj->sect = 0;
                                res = FR_OK;
                        }
                        if (res == FR_OK) {                             /* A valid entry is found */
                                get_fileinfo(dj, fno);          /* Get the object information */
                                res = dir_next(dj, 0);          /* Increment index for next */
                                if (res == FR_NO_FILE) {
                                        dj->sect = 0;
                                        res = FR_OK;
                                }
                        }
                        FREE_BUF();
                }
        }

        LEAVE_FF(dj->fs, res);
}



#if _FS_MINIMIZE == 0
/*-----------------------------------------------------------------------*/
/* Get File Status                                                       */
/*-----------------------------------------------------------------------*/

FRESULT f_stat (
        const TCHAR *path,      /* Pointer to the file path */
        FILINFO *fno            /* Pointer to file information to return */
)
{
        FRESULT res;
        DIR dj;
        DEF_NAMEBUF;


        res = chk_mounted(&path, &dj.fs, 0);
        if (res == FR_OK) {
                INIT_BUF(dj);
                res = follow_path(&dj, path);   /* Follow the file path */
                if (res == FR_OK) {                             /* Follow completed */
                        if (dj.dir)             /* Found an object */
                                get_fileinfo(&dj, fno);
                        else                    /* It is root dir */
                                res = FR_INVALID_NAME;
                }
                FREE_BUF();
        }

        LEAVE_FF(dj.fs, res);
}



#if !_FS_READONLY
/*-----------------------------------------------------------------------*/
/* Get Number of Free Clusters                                           */
/*-----------------------------------------------------------------------*/

FRESULT f_getfree (
        const TCHAR *path,      /* Pointer to the logical drive number (root dir) */
        DWORD *nclst,           /* Pointer to the variable to return number of free clusters */
        FATFS **fatfs           /* Pointer to pointer to corresponding file system object to return */
)
{
        FRESULT res;
        DWORD n, clst, sect, stat;
        UINT i;
        BYTE fat, *p;


        /* Get drive number */
        res = chk_mounted(&path, fatfs, 0);
        if (res == FR_OK) {
                /* If free_clust is valid, return it without full cluster scan */
                if ((*fatfs)->free_clust <= (*fatfs)->n_fatent - 2) {
                        *nclst = (*fatfs)->free_clust;
                } else {
                        /* Get number of free clusters */
                        fat = (*fatfs)->fs_type;
                        n = 0;
                        if (fat == FS_FAT12) {
                                clst = 2;
                                do {
                                        stat = get_fat(*fatfs, clst);
                                        if (stat == 0xFFFFFFFF) { res = FR_DISK_ERR; break; }
                                        if (stat == 1) { res = FR_INT_ERR; break; }
                                        if (stat == 0) n++;
                                } while (++clst < (*fatfs)->n_fatent);
                        } else {
                                clst = (*fatfs)->n_fatent;
                                sect = (*fatfs)->fatbase;
                                i = 0; p = 0;
                                do {
                                        if (!i) {
                                                res = move_window(*fatfs, sect++);
                                                if (res != FR_OK) break;
                                                p = (*fatfs)->win;
                                                i = SS(*fatfs);
                                        }
                                        if (fat == FS_FAT16) {
                                                if (LD_WORD(p) == 0) n++;
                                                p += 2; i -= 2;
                                        } else {
                                                if ((LD_DWORD(p) & 0x0FFFFFFF) == 0) n++;
                                                p += 4; i -= 4;
                                        }
                                } while (--clst);
                        }
                        (*fatfs)->free_clust = n;
                        if (fat == FS_FAT32) (*fatfs)->fsi_flag = 1;
                        *nclst = n;
                }
        }
        LEAVE_FF(*fatfs, res);
}




/*-----------------------------------------------------------------------*/
/* Truncate File                                                         */
/*-----------------------------------------------------------------------*/

FRESULT f_truncate (
        FIL *fp         /* Pointer to the file object */
)
{
        FRESULT res;
        DWORD ncl;


        res = validate(fp->fs, fp->id);         /* Check validity of the object */
        if (res == FR_OK) {
                if (fp->flag & FA__ERROR) {                     /* Check abort flag */
                        res = FR_INT_ERR;
                } else {
                        if (!(fp->flag & FA_WRITE))             /* Check access mode */
                                res = FR_DENIED;
                }
        }
        if (res == FR_OK) {
                if (fp->fsize > fp->fptr) {
                        fp->fsize = fp->fptr;   /* Set file size to current R/W point */
                        fp->flag |= FA__WRITTEN;
                        if (fp->fptr == 0) {    /* When set file size to zero, remove entire cluster chain */
                                res = remove_chain(fp->fs, fp->org_clust);
                                fp->org_clust = 0;
                        } else {                                /* When truncate a part of the file, remove remaining clusters */
                                ncl = get_fat(fp->fs, fp->curr_clust);
                                res = FR_OK;
                                if (ncl == 0xFFFFFFFF) res = FR_DISK_ERR;
                                if (ncl == 1) res = FR_INT_ERR;
                                if (res == FR_OK && ncl < fp->fs->n_fatent) {
                                        res = put_fat(fp->fs, fp->curr_clust, 0x0FFFFFFF);
                                        if (res == FR_OK) res = remove_chain(fp->fs, ncl);
                                }
                        }
                }
                if (res != FR_OK) fp->flag |= FA__ERROR;
        }

        LEAVE_FF(fp->fs, res);
}




/*-----------------------------------------------------------------------*/
/* Delete a File or Directory                                            */
/*-----------------------------------------------------------------------*/

FRESULT f_unlink (
        const TCHAR *path               /* Pointer to the file or directory path */
)
{
        FRESULT res;
        DIR dj, sdj;
        BYTE *dir;
        DWORD dclst;
        DEF_NAMEBUF;


        res = chk_mounted(&path, &dj.fs, 1);
        if (res == FR_OK) {
                INIT_BUF(dj);
                res = follow_path(&dj, path);           /* Follow the file path */
                if (_FS_RPATH && res == FR_OK && (dj.fn[NS] & NS_DOT))
                        res = FR_INVALID_NAME;                  /* Cannot remove dot entry */
#if _FS_SHARE
                if (res == FR_OK) res = chk_lock(&dj, 2);       /* Cannot remove open file */
#endif
                if (res == FR_OK) {                                     /* The object is accessible */
                        dir = dj.dir;
                        if (!dir) {
                                res = FR_INVALID_NAME;          /* Cannot remove the start directory */
                        } else {
                                if (dir[DIR_Attr] & AM_RDO)
                                        res = FR_DENIED;                /* Cannot remove R/O object */
                        }
                        dclst = LD_CLUST(dir);
                        if (res == FR_OK && (dir[DIR_Attr] & AM_DIR)) { /* Is it a sub-dir? */
                                if (dclst < 2) {
                                        res = FR_INT_ERR;
                                } else {
                                        mem_cpy(&sdj, &dj, sizeof(DIR));        /* Check if the sub-dir is empty or not */
                                        sdj.sclust = dclst;
                                        res = dir_sdi(&sdj, 2);         /* Exclude dot entries */
                                        if (res == FR_OK) {
                                                res = dir_read(&sdj);
                                                if (res == FR_OK                        /* Not empty dir */
#if _FS_RPATH
                                                || dclst == sdj.fs->cdir        /* Current dir */
#endif
                                                ) res = FR_DENIED;
                                                if (res == FR_NO_FILE) res = FR_OK;     /* Empty */
                                        }
                                }
                        }
                        if (res == FR_OK) {
                                res = dir_remove(&dj);          /* Remove the directory entry */
                                if (res == FR_OK) {
                                        if (dclst)                              /* Remove the cluster chain if exist */
                                                res = remove_chain(dj.fs, dclst);
                                        if (res == FR_OK) res = sync(dj.fs);
                                }
                        }
                }
                FREE_BUF();
        }
        LEAVE_FF(dj.fs, res);
}




/*-----------------------------------------------------------------------*/
/* Create a Directory                                                    */
/*-----------------------------------------------------------------------*/

FRESULT f_mkdir (
        const TCHAR *path               /* Pointer to the directory path */
)
{
        FRESULT res;
        DIR dj;
        BYTE *dir, n;
        DWORD dsc, dcl, pcl, tim = get_fattime();
        DEF_NAMEBUF;


        res = chk_mounted(&path, &dj.fs, 1);
        if (res == FR_OK) {
                INIT_BUF(dj);
                res = follow_path(&dj, path);                   /* Follow the file path */
                if (res == FR_OK) res = FR_EXIST;               /* Any object with same name is already existing */
                if (_FS_RPATH && res == FR_NO_FILE && (dj.fn[NS] & NS_DOT))
                        res = FR_INVALID_NAME;
                if (res == FR_NO_FILE) {                                /* Can create a new directory */
                        dcl = create_chain(dj.fs, 0);           /* Allocate a cluster for the new directory table */
                        res = FR_OK;
                        if (dcl == 0) res = FR_DENIED;          /* No space to allocate a new cluster */
                        if (dcl == 1) res = FR_INT_ERR;
                        if (dcl == 0xFFFFFFFF) res = FR_DISK_ERR;
                        if (res == FR_OK)                                       /* Flush FAT */
                                res = move_window(dj.fs, 0);
                        if (res == FR_OK) {                                     /* Initialize the new directory table */
                                dsc = clust2sect(dj.fs, dcl);
                                dir = dj.fs->win;
                                mem_set(dir, 0, SS(dj.fs));
                                mem_set(dir+DIR_Name, ' ', 8+3);        /* Create "." entry */
                                dir[DIR_Name] = '.';
                                dir[DIR_Attr] = AM_DIR;
                                ST_DWORD(dir+DIR_WrtTime, tim);
                                ST_CLUST(dir, dcl);
                                mem_cpy(dir+32, dir, 32);                       /* Create ".." entry */
                                dir[33] = '.'; pcl = dj.sclust;
                                if (dj.fs->fs_type == FS_FAT32 && pcl == dj.fs->dirbase)
                                        pcl = 0;
                                ST_CLUST(dir+32, pcl);
                                for (n = dj.fs->csize; n; n--) {        /* Write dot entries and clear following sectors */
                                        dj.fs->winsect = dsc++;
                                        dj.fs->wflag = 1;
                                        res = move_window(dj.fs, 0);
                                        if (res != FR_OK) break;
                                        mem_set(dir, 0, SS(dj.fs));
                                }
                        }
                        if (res == FR_OK) res = dir_register(&dj);      /* Register the object to the directoy */
                        if (res != FR_OK) {
                                remove_chain(dj.fs, dcl);                       /* Could not register, remove cluster chain */
                        } else {
                                dir = dj.dir;
                                dir[DIR_Attr] = AM_DIR;                         /* Attribute */
                                ST_DWORD(dir+DIR_WrtTime, tim);         /* Created time */
                                ST_CLUST(dir, dcl);                                     /* Table start cluster */
                                dj.fs->wflag = 1;
                                res = sync(dj.fs);
                        }
                }
                FREE_BUF();
        }

        LEAVE_FF(dj.fs, res);
}




/*-----------------------------------------------------------------------*/
/* Change Attribute                                                      */
/*-----------------------------------------------------------------------*/

FRESULT f_chmod (
        const TCHAR *path,      /* Pointer to the file path */
        BYTE value,                     /* Attribute bits */
        BYTE mask                       /* Attribute mask to change */
)
{
        FRESULT res;
        DIR dj;
        BYTE *dir;
        DEF_NAMEBUF;


        res = chk_mounted(&path, &dj.fs, 1);
        if (res == FR_OK) {
                INIT_BUF(dj);
                res = follow_path(&dj, path);           /* Follow the file path */
                FREE_BUF();
                if (_FS_RPATH && res == FR_OK && (dj.fn[NS] & NS_DOT))
                        res = FR_INVALID_NAME;
                if (res == FR_OK) {
                        dir = dj.dir;
                        if (!dir) {                                             /* Is it a root directory? */
                                res = FR_INVALID_NAME;
                        } else {                                                /* File or sub directory */
                                mask &= AM_RDO|AM_HID|AM_SYS|AM_ARC;    /* Valid attribute mask */
                                dir[DIR_Attr] = (value & mask) | (dir[DIR_Attr] & (BYTE)~mask); /* Apply attribute change */
                                dj.fs->wflag = 1;
                                res = sync(dj.fs);
                        }
                }
        }

        LEAVE_FF(dj.fs, res);
}




/*-----------------------------------------------------------------------*/
/* Change Timestamp                                                      */
/*-----------------------------------------------------------------------*/

FRESULT f_utime (
        const TCHAR *path,      /* Pointer to the file/directory name */
        const FILINFO *fno      /* Pointer to the time stamp to be set */
)
{
        FRESULT res;
        DIR dj;
        BYTE *dir;
        DEF_NAMEBUF;


        res = chk_mounted(&path, &dj.fs, 1);
        if (res == FR_OK) {
                INIT_BUF(dj);
                res = follow_path(&dj, path);   /* Follow the file path */
                FREE_BUF();
                if (_FS_RPATH && res == FR_OK && (dj.fn[NS] & NS_DOT))
                        res = FR_INVALID_NAME;
                if (res == FR_OK) {
                        dir = dj.dir;
                        if (!dir) {                                     /* Root directory */
                                res = FR_INVALID_NAME;
                        } else {                                        /* File or sub-directory */
                                ST_WORD(dir+DIR_WrtTime, fno->ftime);
                                ST_WORD(dir+DIR_WrtDate, fno->fdate);
                                dj.fs->wflag = 1;
                                res = sync(dj.fs);
                        }
                }
        }

        LEAVE_FF(dj.fs, res);
}




/*-----------------------------------------------------------------------*/
/* Rename File/Directory                                                 */
/*-----------------------------------------------------------------------*/

FRESULT f_rename (
        const TCHAR *path_old,  /* Pointer to the old name */
        const TCHAR *path_new   /* Pointer to the new name */
)
{
        FRESULT res;
        DIR djo, djn;
        BYTE buf[21], *dir;
        DWORD dw;
        DEF_NAMEBUF;


        res = chk_mounted(&path_old, &djo.fs, 1);
        if (res == FR_OK) {
                djn.fs = djo.fs;
                INIT_BUF(djo);
                res = follow_path(&djo, path_old);              /* Check old object */
                if (_FS_RPATH && res == FR_OK && (djo.fn[NS] & NS_DOT))
                        res = FR_INVALID_NAME;
#if _FS_SHARE
                if (res == FR_OK) res = chk_lock(&djo, 2);
#endif
                if (res == FR_OK) {                                             /* Old object is found */
                        if (!djo.dir) {                                         /* Is root dir? */
                                res = FR_NO_FILE;
                        } else {
                                mem_cpy(buf, djo.dir+DIR_Attr, 21);             /* Save the object information except for name */
                                mem_cpy(&djn, &djo, sizeof(DIR));               /* Check new object */
                                res = follow_path(&djn, path_new);
                                if (res == FR_OK) res = FR_EXIST;               /* The new object name is already existing */
                                if (res == FR_NO_FILE) {                                /* Is it a valid path and no name collision? */
/* Start critical section that any interruption or error can cause cross-link */
                                        res = dir_register(&djn);                       /* Register the new entry */
                                        if (res == FR_OK) {
                                                dir = djn.dir;                                  /* Copy object information except for name */
                                                mem_cpy(dir+13, buf+2, 19);
                                                dir[DIR_Attr] = buf[0] | AM_ARC;
                                                djo.fs->wflag = 1;
                                                if (djo.sclust != djn.sclust && (dir[DIR_Attr] & AM_DIR)) {             /* Update .. entry in the directory if needed */
                                                        dw = clust2sect(djn.fs, LD_CLUST(dir));
                                                        if (!dw) {
                                                                res = FR_INT_ERR;
                                                        } else {
                                                                res = move_window(djn.fs, dw);
                                                                dir = djn.fs->win+32;   /* .. entry */
                                                                if (res == FR_OK && dir[1] == '.') {
                                                                        dw = (djn.fs->fs_type == FS_FAT32 && djn.sclust == djn.fs->dirbase) ? 0 : djn.sclust;
                                                                        ST_CLUST(dir, dw);
                                                                        djn.fs->wflag = 1;
                                                                }
                                                        }
                                                }
                                                if (res == FR_OK) {
                                                        res = dir_remove(&djo);         /* Remove old entry */
                                                        if (res == FR_OK)
                                                                res = sync(djo.fs);
                                                }
                                        }
/* End critical section */
                                }
                        }
                }
                FREE_BUF();
        }
        LEAVE_FF(djo.fs, res);
}

#endif /* !_FS_READONLY */
#endif /* _FS_MINIMIZE == 0 */
#endif /* _FS_MINIMIZE <= 1 */
#endif /* _FS_MINIMIZE <= 2 */



/*-----------------------------------------------------------------------*/
/* Forward data to the stream directly (available on only tiny cfg)      */
/*-----------------------------------------------------------------------*/
#if _USE_FORWARD && _FS_TINY

FRESULT f_forward (
        FIL *fp,                                                /* Pointer to the file object */
        UINT (*func)(const BYTE*,UINT), /* Pointer to the streaming function */
        UINT btr,                                               /* Number of bytes to forward */
        UINT *bf                                                /* Pointer to number of bytes forwarded */
)
{
        FRESULT res;
        DWORD remain, clst, sect;
        UINT rcnt;
        BYTE csect;


        *bf = 0;        /* Initialize byte counter */

        res = validate(fp->fs, fp->id);                                 /* Check validity of the object */
        if (res != FR_OK) LEAVE_FF(fp->fs, res);
        if (fp->flag & FA__ERROR)                                               /* Check error flag */
                LEAVE_FF(fp->fs, FR_INT_ERR);
        if (!(fp->flag & FA_READ))                                              /* Check access mode */
                LEAVE_FF(fp->fs, FR_DENIED);

        remain = fp->fsize - fp->fptr;
        if (btr > remain) btr = (UINT)remain;                   /* Truncate btr by remaining bytes */

        for ( ;  btr && (*func)(0, 0);                                  /* Repeat until all data transferred or stream becomes busy */
                fp->fptr += rcnt, *bf += rcnt, btr -= rcnt) {
                csect = (BYTE)(fp->fptr / SS(fp->fs) & (fp->fs->csize - 1));    /* Sector offset in the cluster */
                if ((fp->fptr % SS(fp->fs)) == 0) {                     /* On the sector boundary? */
                        if (!csect) {                                                   /* On the cluster boundary? */
                                clst = (fp->fptr == 0) ?                        /* On the top of the file? */
                                        fp->org_clust : get_fat(fp->fs, fp->curr_clust);
                                if (clst <= 1) ABORT(fp->fs, FR_INT_ERR);
                                if (clst == 0xFFFFFFFF) ABORT(fp->fs, FR_DISK_ERR);
                                fp->curr_clust = clst;                          /* Update current cluster */
                        }
                }
                sect = clust2sect(fp->fs, fp->curr_clust);      /* Get current data sector */
                if (!sect) ABORT(fp->fs, FR_INT_ERR);
                sect += csect;
                if (move_window(fp->fs, sect))                          /* Move sector window */
                        ABORT(fp->fs, FR_DISK_ERR);
                fp->dsect = sect;
                rcnt = SS(fp->fs) - (WORD)(fp->fptr % SS(fp->fs));      /* Forward data from sector window */
                if (rcnt > btr) rcnt = btr;
                rcnt = (*func)(&fp->fs->win[(WORD)fp->fptr % SS(fp->fs)], rcnt);
                if (!rcnt) ABORT(fp->fs, FR_INT_ERR);
        }

        LEAVE_FF(fp->fs, FR_OK);
}
#endif /* _USE_FORWARD */



#if _USE_MKFS && !_FS_READONLY
/*-----------------------------------------------------------------------*/
/* Create File System on the Drive                                       */
/*-----------------------------------------------------------------------*/
#define N_ROOTDIR       512             /* Multiple of 32 */
#define N_FATS          1               /* 1 or 2 */


FRESULT f_mkfs (
        BYTE drv,               /* Logical drive number */
        BYTE sfd,               /* Partitioning rule 0:FDISK, 1:SFD */
        UINT au                 /* Allocation unit size [bytes] */
)
{
        static const WORD vst[] = { 1024,   512,  256,  128,   64,    32,   16,    8,    4,    2,   0};
        static const WORD cst[] = {32768, 16384, 8192, 4096, 2048, 16384, 8192, 4096, 2048, 1024, 512};
        BYTE fmt, md, *tbl;
        DWORD n_clst, vs, n, wsect;
        UINT i;
        DWORD b_vol, b_fat, b_dir, b_data;      /* Offset (LBA) */
        DWORD n_vol, n_rsv, n_fat, n_dir;       /* Size */
        FATFS *fs;
        DSTATUS stat;


        /* Check mounted drive and clear work area */
        if (drv >= _VOLUMES) return FR_INVALID_DRIVE;
        fs = FatFs[drv];
        if (!fs) return FR_NOT_ENABLED;
        fs->fs_type = 0;
        drv = LD2PD(drv);

        /* Get disk statics */
        stat = disk_initialize(drv);
        if (stat & STA_NOINIT) return FR_NOT_READY;
        if (stat & STA_PROTECT) return FR_WRITE_PROTECTED;
#if _MAX_SS != 512                                      /* Get disk sector size */
        if (disk_ioctl(drv, GET_SECTOR_SIZE, &SS(fs)) != RES_OK)
                return FR_DISK_ERR;
#endif
        if (disk_ioctl(drv, GET_SECTOR_COUNT, &n_vol) != RES_OK || n_vol < 128)
                return FR_DISK_ERR;
        b_vol = (sfd) ? 0 : 63; /* Volume start sector */
        n_vol -= b_vol;
        if (au & (au - 1)) au = 0;              /* Check validity of the allocation unit size */
        if (!au) {                                              /* AU auto selection */
                vs = n_vol / (2000 / (SS(fs) / 512));
                for (i = 0; vs < vst[i]; i++) ;
                au = cst[i];
        }
        au /= SS(fs);           /* Number of sectors per cluster */
        if (au == 0) au = 1;
        if (au > 128) au = 128;

        /* Pre-compute number of clusters and FAT syb-type */
        n_clst = n_vol / au;
        fmt = FS_FAT12;
        if (n_clst >= MIN_FAT16) fmt = FS_FAT16;
        if (n_clst >= MIN_FAT32) fmt = FS_FAT32;

        /* Determine offset and size of FAT structure */
        if (fmt == FS_FAT32) {
                n_fat = ((n_clst * 4) + 8 + SS(fs) - 1) / SS(fs);
                n_rsv = 32;
                n_dir = 0;
        } else {
                n_fat = (fmt == FS_FAT12) ? (n_clst * 3 + 1) / 2 + 3 : (n_clst * 2) + 4;
                n_fat = (n_fat + SS(fs) - 1) / SS(fs);
                n_rsv = 1;
                n_dir = N_ROOTDIR * 32UL / SS(fs);
        }
        b_fat = b_vol + n_rsv;                          /* FAT area start sector */
        b_dir = b_fat + n_fat * N_FATS;         /* Directory area start sector */
        b_data = b_dir + n_dir;                         /* Data area start sector */
        if (n_vol < b_data + au) return FR_MKFS_ABORTED;        /* Too small volume */

        /* Align data start sector to erase block boundary (for flash memory media) */
        if (disk_ioctl(drv, GET_BLOCK_SIZE, &n) != RES_OK || !n || n > 32768) n = 1;
        n = (b_data + n - 1) & ~(n - 1);        /* Next nearest erase block from current data start */
        n = (n - b_data) / N_FATS;
        if (fmt == FS_FAT32) {          /* FAT32: Move FAT offset */
                n_rsv += n;
                b_fat += n;
        } else {                                        /* FAT12/16: Expand FAT size */
                n_fat += n;
        }

        /* Determine number of cluster and final check of validity of the FAT sub-type */
        n_clst = (n_vol - n_rsv - n_fat * N_FATS - n_dir) / au;
        if (   (fmt == FS_FAT16 && n_clst < MIN_FAT16)
                || (fmt == FS_FAT32 && n_clst < MIN_FAT32))
                return FR_MKFS_ABORTED;

        /* Create partition table if required */
        if (sfd) {
                md = 0xF0;
        } else {
                DWORD n_disk = b_vol + n_vol;

                mem_set(fs->win, 0, SS(fs));
                tbl = fs->win+MBR_Table;
                ST_DWORD(tbl, 0x00010180);                      /* Partition start in CHS */
                if (n_disk < 63UL * 255 * 1024) {       /* Partition end in CHS */
                        n_disk = n_disk / 63 / 255;
                        tbl[7] = (BYTE)n_disk;
                        tbl[6] = (BYTE)((n_disk >> 2) | 63);
                } else {
                        ST_WORD(&tbl[6], 0xFFFF);
                }
                tbl[5] = 254;
                if (fmt != FS_FAT32)                            /* System ID */
                        tbl[4] = (n_vol < 0x10000) ? 0x04 : 0x06;
                else
                        tbl[4] = 0x0c;
                ST_DWORD(tbl+8, 63);                            /* Partition start in LBA */
                ST_DWORD(tbl+12, n_vol);                        /* Partition size in LBA */
                ST_WORD(tbl+64, 0xAA55);                        /* Signature */
                if (disk_write(drv, fs->win, 0, 1) != RES_OK)
                        return FR_DISK_ERR;
                md = 0xF8;
        }

        /* Create volume boot record */
        tbl = fs->win;                                                  /* Clear sector */
        mem_set(tbl, 0, SS(fs));
        mem_cpy(tbl, "\xEB\xFE\x90" "MSDOS5.0", 11);/* Boot code, OEM name */
        i = SS(fs);                                                             /* Sector size */
        ST_WORD(tbl+BPB_BytsPerSec, i);
        tbl[BPB_SecPerClus] = (BYTE)au;                 /* Sectors per cluster */
        ST_WORD(tbl+BPB_RsvdSecCnt, n_rsv);             /* Reserved sectors */
        tbl[BPB_NumFATs] = N_FATS;                              /* Number of FATs */
        i = (fmt == FS_FAT32) ? 0 : N_ROOTDIR;  /* Number of rootdir entries */
        ST_WORD(tbl+BPB_RootEntCnt, i);
        if (n_vol < 0x10000) {                                  /* Number of total sectors */
                ST_WORD(tbl+BPB_TotSec16, n_vol);
        } else {
                ST_DWORD(tbl+BPB_TotSec32, n_vol);
        }
        tbl[BPB_Media] = md;                                    /* Media descriptor */
        ST_WORD(tbl+BPB_SecPerTrk, 63);                 /* Number of sectors per track */
        ST_WORD(tbl+BPB_NumHeads, 255);                 /* Number of heads */
        ST_DWORD(tbl+BPB_HiddSec, b_vol);               /* Hidden sectors */
        n = get_fattime();                                              /* Use current time as VSN */
        if (fmt == FS_FAT32) {
                ST_DWORD(tbl+BS_VolID32, n);            /* VSN */
                ST_DWORD(tbl+BPB_FATSz32, n_fat);       /* Number of sectors per FAT */
                ST_DWORD(tbl+BPB_RootClus, 2);          /* Root directory start cluster (2) */
                ST_WORD(tbl+BPB_FSInfo, 1);                     /* FSInfo record offset (VBR+1) */
                ST_WORD(tbl+BPB_BkBootSec, 6);          /* Backup boot record offset (VBR+6) */
                tbl[BS_DrvNum32] = 0x80;                        /* Drive number */
                tbl[BS_BootSig32] = 0x29;                       /* Extended boot signature */
                mem_cpy(tbl+BS_VolLab32, "NO NAME    " "FAT32   ", 19); /* Volume label, FAT signature */
        } else {
                ST_DWORD(tbl+BS_VolID, n);                      /* VSN */
                ST_WORD(tbl+BPB_FATSz16, n_fat);        /* Number of sectors per FAT */
                tbl[BS_DrvNum] = 0x80;                          /* Drive number */
                tbl[BS_BootSig] = 0x29;                         /* Extended boot signature */
                mem_cpy(tbl+BS_VolLab, "NO NAME    " "FAT     ", 19);   /* Volume label, FAT signature */
        }
        ST_WORD(tbl+BS_55AA, 0xAA55);                   /* Signature (Offset is fixed here regardless of sector size) */
        if (disk_write(drv, tbl, b_vol, 1) != RES_OK)/* Write original (VBR) */
                return FR_DISK_ERR;
        if (fmt == FS_FAT32)                                    /* Write backup (VBR+6) */
                disk_write(drv, tbl, b_vol + 6, 1);

        /* Initialize FAT area */
        wsect = b_fat;
        for (i = 0; i < N_FATS; i++) {
                mem_set(tbl, 0, SS(fs));                        /* 1st sector of the FAT  */
                n = md;                                                         /* Media descriptor byte */
                if (fmt != FS_FAT32) {
                        n |= (fmt == FS_FAT12) ? 0x00FFFF00 : 0xFFFFFF00;
                        ST_DWORD(tbl+0, n);                             /* Reserve cluster #0-1 (FAT12/16) */
                } else {
                        n |= 0xFFFFFF00;
                        ST_DWORD(tbl+0, n);                             /* Reserve cluster #0-1 (FAT32) */
                        ST_DWORD(tbl+4, 0xFFFFFFFF);
                        ST_DWORD(tbl+8, 0x0FFFFFFF);    /* Reserve cluster #2 for root dir */
                }
                if (disk_write(drv, tbl, wsect++, 1) != RES_OK)
                        return FR_DISK_ERR;
                mem_set(tbl, 0, SS(fs));                        /* Fill following FAT entries with zero */
                for (n = 1; n < n_fat; n++) {           /* This loop may take a time on FAT32 volume due to many single sector write */
                        if (disk_write(drv, tbl, wsect++, 1) != RES_OK)
                                return FR_DISK_ERR;
                }
        }

        /* Initialize root directory */
        i = (fmt == FS_FAT32) ? au : n_dir;
        do {
                if (disk_write(drv, tbl, wsect++, 1) != RES_OK)
                        return FR_DISK_ERR;
        } while (--i);

#if _USE_ERASE  /* Erase data area if needed */
        {
                DWORD eb[2];

                eb[0] = wsect; eb[1] = wsect + n_clst * au - 1;
                disk_ioctl(drv, CTRL_ERASE_SECTOR, eb);
        }
#endif

        /* Create FSInfo if needed */
        if (fmt == FS_FAT32) {
                ST_WORD(tbl+BS_55AA, 0xAA55);
                ST_DWORD(tbl+FSI_LeadSig, 0x41615252);
                ST_DWORD(tbl+FSI_StrucSig, 0x61417272);
                ST_DWORD(tbl+FSI_Free_Count, n_clst - 1);
                ST_DWORD(tbl+FSI_Nxt_Free, 0xFFFFFFFF);
                disk_write(drv, tbl, b_vol + 1, 1);     /* Write original (VBR+1) */
                disk_write(drv, tbl, b_vol + 7, 1);     /* Write backup (VBR+7) */
        }

        return (disk_ioctl(drv, CTRL_SYNC, (void*)0) == RES_OK) ? FR_OK : FR_DISK_ERR;
}

#endif /* _USE_MKFS && !_FS_READONLY */




#if _USE_STRFUNC
/*-----------------------------------------------------------------------*/
/* Get a string from the file                                            */
/*-----------------------------------------------------------------------*/
TCHAR* f_gets (
        TCHAR* buff,    /* Pointer to the string buffer to read */
        int len,                /* Size of string buffer (characters) */
        FIL* fil                /* Pointer to the file object */
)
{
        int n = 0;
        TCHAR c, *p = buff;
        BYTE s[2];
        UINT rc;


        while (n < len - 1) {                   /* Read bytes until buffer gets filled */
                f_read(fil, s, 1, &rc);
                if (rc != 1) break;                     /* Break on EOF or error */
                c = s[0];
#if _LFN_UNICODE                                        /* Read a character in UTF-8 encoding */
                if (c >= 0x80) {
                        if (c < 0xC0) continue; /* Skip stray trailer */
                        if (c < 0xE0) {                 /* Two-byte sequense */
                                f_read(fil, s, 1, &rc);
                                if (rc != 1) break;
                                c = ((c & 0x1F) << 6) | (s[0] & 0x3F);
                                if (c < 0x80) c = '?';
                        } else {
                                if (c < 0xF0) {         /* Three-byte sequense */
                                        f_read(fil, s, 2, &rc);
                                        if (rc != 2) break;
                                        c = (c << 12) | ((s[0] & 0x3F) << 6) | (s[1] & 0x3F);
                                        if (c < 0x800) c = '?';
                                } else {                        /* Reject four-byte sequense */
                                        c = '?';
                                }
                        }
                }
#endif
#if _USE_STRFUNC >= 2
                if (c == '\r') continue;        /* Strip '\r' */
#endif
                *p++ = c;
                n++;
                if (c == '\n') break;           /* Break on EOL */
        }
        *p = 0;
        return n ? buff : 0;                    /* When no data read (eof or error), return with error. */
}



#if !_FS_READONLY
#include <stdarg.h>
/*-----------------------------------------------------------------------*/
/* Put a character to the file                                           */
/*-----------------------------------------------------------------------*/
int f_putc (
        TCHAR c,        /* A character to be output */
        FIL* fil        /* Pointer to the file object */
)
{
        UINT bw, btw;
        BYTE s[3];


#if _USE_STRFUNC >= 2
        if (c == '\n') f_putc ('\r', fil);      /* LF -> CRLF conversion */
#endif

#if _LFN_UNICODE        /* Write the character in UTF-8 encoding */
        if (c < 0x80) {                 /* 7-bit */
                s[0] = (BYTE)c;
                btw = 1;
        } else {
                if (c < 0x800) {        /* 11-bit */
                        s[0] = (BYTE)(0xC0 | (c >> 6));
                        s[1] = (BYTE)(0x80 | (c & 0x3F));
                        btw = 2;
                } else {                        /* 16-bit */
                        s[0] = (BYTE)(0xE0 | (c >> 12));
                        s[1] = (BYTE)(0x80 | ((c >> 6) & 0x3F));
                        s[2] = (BYTE)(0x80 | (c & 0x3F));
                        btw = 3;
                }
        }
#else                           /* Write the character without conversion */
        s[0] = (BYTE)c;
        btw = 1;
#endif
        f_write(fil, s, btw, &bw);              /* Write the char to the file */
        return (bw == btw) ? 1 : EOF;   /* Return the result */
}




/*-----------------------------------------------------------------------*/
/* Put a string to the file                                              */
/*-----------------------------------------------------------------------*/
int f_puts (
        const TCHAR* str,       /* Pointer to the string to be output */
        FIL* fil                        /* Pointer to the file object */
)
{
        int n;


        for (n = 0; *str; str++, n++) {
                if (f_putc(*str, fil) == EOF) return EOF;
        }
        return n;
}




/*-----------------------------------------------------------------------*/
/* Put a formatted string to the file                                    */
/*-----------------------------------------------------------------------*/
int f_printf (
        FIL* fil,                       /* Pointer to the file object */
        const TCHAR* str,       /* Pointer to the format string */
        ...                                     /* Optional arguments... */
)
{
        va_list arp;
        BYTE f, r;
        UINT i, w;
        ULONG val;
        TCHAR c, d, s[16];
        int res, cc;


        va_start(arp, str);

        for (cc = res = 0; cc != EOF; res += cc) {
                c = *str++;
                if (c == 0) break;                      /* End of string */
                if (c != '%') {                         /* Non escape character */
                        cc = f_putc(c, fil);
                        if (cc != EOF) cc = 1;
                        continue;
                }
                w = f = 0;
                c = *str++;
                if (c == '0') {                         /* Flag: '0' padding */
                        f = 1; c = *str++;
                }
                while (IsDigit(c)) {            /* Precision */
                        w = w * 10 + c - '0';
                        c = *str++;
                }
                if (c == 'l' || c == 'L') {     /* Prefix: Size is long int */
                        f |= 2; c = *str++;
                }
                if (!c) break;
                d = c;
                if (IsLower(d)) d -= 0x20;
                switch (d) {                            /* Type is... */
                case 'S' :                                      /* String */
                        cc = f_puts(va_arg(arp, TCHAR*), fil); continue;
                case 'C' :                                      /* Character */
                        cc = f_putc((TCHAR)va_arg(arp, int), fil); continue;
                case 'B' :                                      /* Binary */
                        r = 2; break;
                case 'O' :                                      /* Octal */
                        r = 8; break;
                case 'D' :                                      /* Signed decimal */
                case 'U' :                                      /* Unsigned decimal */
                        r = 10; break;
                case 'X' :                                      /* Hexdecimal */
                        r = 16; break;
                default:                                        /* Unknown */
                        cc = f_putc(c, fil); continue;
                }

                /* Get an argument */
                val = (f & 2) ? va_arg(arp, long) : ((d == 'D') ? (long)va_arg(arp, int) : va_arg(arp, unsigned int));
                if (d == 'D' && (val & 0x80000000)) {
                        val = 0 - val;
                        f |= 4;
                }
                /* Put it in numeral string */
                i = 0;
                do {
                        d = (TCHAR)(val % r); val /= r;
                        if (d > 9) {
                                d += 7;
                                if (c == 'x') d += 0x20;
                        }
                        s[i++] = d + '0';
                } while (val && i < sizeof(s) / sizeof(s[0]));
                if (f & 4) s[i++] = '-';
                cc = 0;
                while (i < w-- && cc != EOF) {
                        cc = f_putc((TCHAR)((f & 1) ? '0' : ' '), fil);
                        res++;
                }
                do {
                        cc = f_putc(s[--i], fil); 
                        res++;
                } while (i && cc != EOF);
                if (cc != EOF) cc = 0;
        }

        va_end(arp);
        return (cc == EOF) ? cc : res;
}

#endif /* !_FS_READONLY */
#endif /* _USE_STRFUNC */
